You can take bits from both carb and EFI motors and make one good one.
Take care about mixing some bits from tall and short deck versions though.
Read this stuff about 20/22R engines to tell them apart and what bits interchange.
http://ourworld.compuserve.com/homepages/stepho/eng20r.htm
I don't know too much about the 22R myself (we only got it for one year here in Australia and only as the EFI 22R-E) but I wrote up that page from info given to me by some knowledgable Americans.
You also have the option of running the EFI version in your RA65.
The 4A-GE would have required wiring up the computer too, so you were already considering this (possibly without knowing).
Wiring up the computer isn't all that hard.
Also need to upgrade the fuel pump to an EFI fuel pump.
Might also need to double check whether the later model engine mounts bosses are in the same place as your old engine.
You can also consider a crate engine.
There's about half a dozen engine builders that specialise in building street and race 22R's.
- Stepho