So here is a lil update. A bit on the actual process and pics to go with. The first rule was to not in any way alter the engine bay in any way. No banging the firewall, side walls or front end. It had to appear to be as if the RB20 could have been a factory option as it was in the Z31. Unfortunately there was one area that had to be massaged but that was for the gear box tunnel just a bit to make room for the starter. I accepted this since it wasnt a great change the car and if Nissan had the RB20 in the S12, they would have been forced to do the same. Before this time I got in touch with a bloke who first did the RB20 swap in a S12 that anyone has had proof or ever knew of. He was a really cool Aussie chap known on a couple of S12 forums as ib6ub9. Anyway, everything he told me didnt work out. Though, there wasnt that much he told me that was in explicit detail. But I came to realize a couple reasons as to why nothing he said was working for me. One of the big reasons was due to the RHD/LHD setups. It may not seem like much, but with all the vacuum lines and piping for the IC and exhaust, things were a little uneven when matching up. But the biggest reason was due to the fact that I have a Nissan 200sx SE that was available only in the US. This was equipped with a VG30E. So seeing that a V6 will be totally different than a CA, it makes sense that the front cross member and motor mount setup would be entirely different.
The next set of pics will be of the process. Feel free to ask.
USDM driver's side



USDM passenger's side


Front sway bar will not work since it would hit the sump. One nice thing is that the RBs are front sump just as the S12 is. The VGs in a Z31 were rear sump but when they decided to put it into a S12, they had to make a new sump and adjust the oil pickup so that it could fit correctly within the S12's parameters. Thankfully though, with the placement we obtained with the motor, it cleared the rack and such without issue.
USDM driver's side. Gearbox on the right of the pic.

USDM passenger's side. Gearbox on the left of the pic.
