[N1ceDrgn]

This reply is not in defense of, it's only a statement of what I've seen, that it can be done and what's needed to make it happen...
As far as an RB swap goes, it can be put in an S13. The only mod's that have to be done really are the cross-member, needs to be manufactured. Unless there's a company out there making them now but last I knew it was all home made. Then with the exhaust/ turbos setup, here stateside, it would 'have to' be top mount. Now, whether you running single or double, I don't know. Running double, is stock, not an upgrade. The only modifications that I saw and worked with was that the firewall needed to be worked over and the engine/ transmission connection sits back further inside the car. With that connection, the transmission mount/ support needs to be fabricated. You do need an RB mission to go with the engine. As far as the wiring harness, you'd need the RB harness and splice it into the S13 harness. All in all the worst part about it is getting the mounts manufactured and then messing with the firewall. Then, the only other thing would be the wiring, if you're not very good at it. When I was overseas, there was a guy I knew that blew a LOT of cash into getting it done and he has nothing but problems with it. There was always something breaking. It can be done, but it turns into an expensive ride to keep up.