The Chevys are tough. First of all there is no physical externel difference between any of the Small Block chevies from the 283 to the 350. The only way to tell the difference is to measure the bore & stroke. Some of the old wrenches could tell by looking at the flywheel end of the crankshaft. (which is not a detail in with the trans already attached.) There is only one difference between the 350 and the 400. The 400 has 6 freeze plugs, where the 350 (and smaller) have 4. (2 per side) Chevy never produced a 383 from the factory. The 383 is a .030 over 350 with a 400 crank installed. Actually, the same goes for the Big Blocks as well. From the 396 to the 454, the block is the same basic casting. The heads are all the same castings as well. The only way to tell the difference in a model would be to look at the decal that the model builder slid on the aircleaner. The factory valve covers on the 502 are a little squarer than the 454, but once again still the same basic block and heads. The 572 has got those wonderful valve covers, but the rest is the same. For myself, the engine in the Tony Foti LAPD Pro-Mod Camaro is one of the best race motors out there. I think I've got about 6 of those kits just for the motors. (Hmmm...probably be easier to just cast the stupid thing at this point.)
I only know enough about the other brands to be dangerous. (too myself).