my honest thoughts on this are just go the 2.2 and get the proper pistons if your going to run a 3037 you will need all the revs you can get tomei make the 2.2 pistons they are 82 mm should be plenty of bore left I know some one who ran this set up with a big rx6 set up and 256 cams and he made 600 hp you will need cams and some head work also consider usinga rb 26 n1 oil pump.
cheers
meggala
http://www.tomei-p.co.jp/
have fun I wish I had the budget to build one a rebuilt 20 will have to do me