Also, don't confuse 22R vs 22RE with early vs late engine. R/RE just determines if it's carbed or EFI the heads are the same for each. The heads are not the same for early vs late engines.

Actually mid '83 you can bolt an EFI manifold to it. The earlier 22r's 80-83 you can't unless  you tap for holes. And 20R heads you can't either unless you get a custom head. As for my question the reason why you can't is because there will be a different centre for the cam to crankshaft. We already had discussed about the different heads and I mentioned them in my initial post. And H8PVMT did answer the question I just didn't read his post correctly.