R18 to R20

I know there are older threads on this, I've just been trying to get some more information on modifying my R18. According to some, you can run certain parts from an R20 (cam, crank, oversized pistons, amongst a few other things). I'm wondering if anyone knows someone who has successfully done this, or has any info on what I can do to find out what will work and what wont.

Thanks!