Originally Posted by 222Doc
well the stock stuff had to deal with like 60hp. you would need a right foot that is lighter than air.
Yes, but that does work and you actually can keep a D25 alive using a 350. Just no lockers, nothing bigger than 33's and a very light right foot when in 4x4. The stock rear axle should be a D41 which is much stronger than the front but if you get on it, the hub keys will likely shear. The D41's are actually just as strong as the similar 2 piece axle versions of the D44 but you have a rather limited gearing selection: 5.38:1.
If you desire to stick with narrow track and the D18 transfercase (which has several good attributes for use in a short Jeep, including the low rear output, available overdrive, and the fact that both pumpkins are in-line which make line selection easier), an offset flanged axle rear D44 out of a 70.5-71 CJ 5/6 is the best stock axle, and a disc brake narrow track D30 for the front from a 76 or later for the front. There are countless other options but none are really bolt-in.
The D18 can handle the power and someplace down the road, you can build a super D18 using a D20 case and the D18 internals. If it was mine, I would do this up front when installing the transmission adapter. I assume by 4 sp you mean the SM465 truck version? That is the best transmission for this conversion and works very well with an overdrive in the D18 and also makes for the shortest transmission length.
Another item that should be addressed is the frame. The 2A's use a lighter gage material than the later CJ's and they were strapped. My experience has been that the strapping was woefully inadequate and they all eventually break if the vehicle is actually used for a Jeep. Box it-entirely!
It will not stop there. You will want Saginaw power steering also and possibly both front and rear disc brakes. In short, a new vehicle with old sheet metal. Or maybe new sheet metal