The rb will be around the same power, but you'll need a r32 crossmember to drop in with it. If you go this route, you may as well get a whole front clip.
You may want to consider a ca18det. They're cheap as hell and unlike the sr, it has an iron block. It's slightly less powerful, but if you upgrade the turbo to that of the stock one on an sr, you'll be making around the same. You can find these ranging from 700-1500 bucks.