Just saw this thread, good to see something for us NA boys!!
FunkyMonkey, you are not alone! ive also got the RB20DE in my R32!
regarding the RB30 conversion, a bloke here in canberra is currently doing one with a NICS RB20 head and a GTR twon turbo zorhst manifold, the only problems so far that he has come across is the mounting points for the exhaust manifold dont quite line up as in the tabs on the manifold are in the completely wrong places, nothing that a couple of hours with a welder wont fix!
also with the RB30, the standard head uses a 2 valve per cylinder system while the actual original pistons have allowances for 4 per cylinder (if u get what i mean confused myself with that one!) and where the timing belt tensioner goes, there is a blocked off section of the engine that just requires to be drilled out and a thread tapped into it
almost makes the conversion sound easy!