Welcome aboard. :sa:
Unless there's an adapter, the t-case will be a model 20, not a 300. The 300 wasn't standard until 1980. The bottom cover on the 300 is nearly flat, the 20 is raised about 1" hight than the bolts. The V-8 will bolt in, make sure you have the correct pilot bushing in the crank. You will need the V-8 specific motor mounts for a CJ, all the way from the frame rail to the engine block (Wagoneer mounts are shorter). www.mountainoffroad.com makes some bombproof aftermarket ones.
Make sure you have a 304 specific flywheel, as the V-8s are externally balanced and require a displacement specific flywheel. You will also need a few minor wiring changes, and the V-8 throttle cable. If it's a factory 2 row radiator it may be marginal.
It's a worth while swap. All AMC V-8s are the same outside dimensions on the block, so you can go all the way to a 401 if you can find one.
Bob
tufcj
