A V8 conversion is going to cause you to hack the radiator mount/grill.
There are a couple of options, including the popular Buick and Vortec V6, that will fit in the existing engine bay.
You can also go with a modern 4 out of a Ford or Chevy.
All conversions will include motor tower mods/replacement, exhaust work, transmission adapters, linkage work, clutch, and rewiring, just to name the biggies. Years ago, one could find a 66-71 CJ wreck and salvage the stock 225 and usually the drivetrain to boot, and drop it in "in mass". these are a rare bird to find now, so that option isn't really viable.
If you are interested in swaps, hit the Novak knowledge center and do some research.
Also, an engine swap in ECJ's is usually accompanied by either a gearing swap or an overdrive, as the rigs are geared low to compensate for the low power output of the stock engine, so that will be another expense.
Personally, I would repair the existing engine, drive it and enjoy it. Later on, after you have worked all the bugs out of it (bad steering, ginky brakes, worn bushings, and the inevitable lift), you can look to upgrading in the power department.