This topic has been covered before but I thought I'd share my take on the project. I've owned 7 Jeeps including 3 Wranglers so I wanted something a little unique for my '94. It's bone stock except for a 2" body lift and completely rust free.
I had a line on a complete CJ front clip, but for some reason the guy sold the fenders to someone else (after he had agreed to sell it all to me). After that, I found another Craigslist ad for a hood and grille from a '79 CJ. $150 later they were sitting in my garage. Essentially rust free, the hood had a few dings and the grille needed a bit of straightening and I stripped them to bare metal for a fresh start. I won't go into details on all that so we can get right into the swap process. From start to finish the entire swap took about 10 hours and I'll describe it here with detail and pics.
First I removed the under hood light and wiring clip. Next I removed the hood and amazingly the torx screws were not seized at all. I kept the Wranger hinges on the body as it's less to have to paint. After that I separated the radiator from the grille (mine was dropped to accommodate the body lift using small brackets). I kept the shroud attached to the radiator and didn't even drain the fluid. There's enough room to lay it out of the way and still not hit the fan. Also the power steering reservoir was unbolted and set aside being careful not to twist the hoses. The body bolt on the bottom of the grille must be removed as does all the grille to fender bolts. These all came of fairly easily. The brackets on the underside of the fenders were loosened and swung out of the way.
The lights were disconnected, including the side markers and the entire harness was fished out from the holes in the grille after carefully undoing the clips that hold the harness in place. There are a couple of ground wires attached to the grille that needed to be disconnected as well. I also disconnected and removed the air intake just to make some room to work. The grille was easily lifted out and away from the Jeep.
Fitting the CJ hood was easy with just one person, I put an old sheet over the fenders to prevent any scratches and had it aligned and bolted in place in just a few minutes. I did trim the lips on the top front of the fenders to prevent rubbing.
Fitting the grille was where all the time consuming work came in. Even with a 2" body lift I used a cutting wheel on my angle grinder to notch the CJ grille to clear the hard lines on the steering box. I also had to grind off two mounts that were welded to the frame under the Wrangler grille as part of the body lift. That took a little time as well.
Once the trimming was done on the bottom side the grille it was fitting in place perfectly using the rear set of holes on the Wrangler's fenders. The amount the fenders are drawn in to fit to the slightly skinnier CJ grille is almost negligible and again was easily accomplished with one person. It seems like the grille does sit a little farther back from the hood than an actual CJ, but the latch and catch do line up perfectly.
Next I used 1/8" thick steel strips 1" wide cut to appropriate lengths to attach the radiator to the CJ grille. Having left the shroud attached made it very easy to get it in the proper location. I used the rows of fins to line up with the grille lines to ensure it looked nice and neat. It does seem like it sits too far to the left but it lines up perfectly with the fan. I also cut about 2" from the upper hose on the radiator side as it was slightly kinked due the the CJ grille sitting 2" farther back than the Wrangler grille.
One thing I didn't expect nor did I read about was what to do about the power steering pump reservoir. There is no room to mount it in the original location because everything sits back farther and the air box is now in the way. There's not really another good place for it without switching to longer hoses so I notched the CJ grille so it tucks inside the grille slightly and still (barely) leaved access to check the fluid level.
I used a 1/4" steel plate to extend the mounting plate under the grille and used a 3/4 body grommet and washers I had from my CJ7 teardown. Everything it tight and secure. I still have to add the support rods but as mentioned in other posted they are not threaded far back enough so a little time with a pipe threading die might be in order.
The wiring harness is fished back in using factory holes and as posted elsewhere the headlights use the same connectors. As for the turn signal/running lights, simply ignore the black (ground) wire as the lamps now get grounded from the grille itself once the two separate ground wires from the harness are reattached to the new grille. On the right side, connect the green wire to the yellow wire on the fixture and on the left side connect the brown wire to the yellow wire on the harness. That will give you the correct wiring. You can clip off the Wrangler sockets and crimp on spade connectors and they'll fit right into the CJ fixture connectors.
New holes must be drilled for the hood bumps on the top of the fenders and also holes must be drilled to mount the hood catches, although you can use one of the existing holes from the bumper. That way they line up perfectly. Be careful where you decide to put the bumps as there are ridges on the underside of the fenders you'll want to avoid. I have an extra hole to patch because of this.
That's really about it. I spray bombed the grille with color and two-part epoxy clear mainly because I wanted the inside of the grille to be painted the correct matching color. I still have to patch the holes in the fenders and once that is done I'll rattle can the color on them as well as the hood but I will have it all shot with clear using the proper method.
As for why do all this? I'm not a huge fan of the square lights but I don't mind them. They reigned supreme for 8 years and are just as distinctive as any Jeep front end. But I love looking out over a CJ hood and now I have something a little close to a CJ to drive daily as I slowly restore a 1985 CJ7 Laredo.