[Bean]

4000GT Wrote:Welding and cutting isnt the issue, as you say its the math and geometry. i dont have experience in setting up race suspension geometry. Ill check autospeed perhaps.

In that case I'd advise you to read the following books as they give you a very good starting point on how to approach the brain aspect of the swap.
If you have the whole rear axle you can remove the swaybar (to make your life a bit easier, it's already pretty heavy to move) and do your own testing and observations of how it behaves in different situations.

http://www.amazon.com/How-Make-Your-Car-...0912656468
http://www.amazon.com/Race-Car-Vehicle-D...0768011272

the first one is in my opinion a very good entry to vehicle dynamics - the fact it's a bit dated on some aspects doesn't outweigh the principle of physics that are well and comprehensively explained for such a short read (and let's be honest our cars are just as dated).

the second one is a bit more in-depth and much brainier math/physics heavy.

both can be found on the net as downloads if you don't want to spend the cash right away or at all.

In my opinion doing proper research, including reading AND understanding the basics is just as crucial as discussing the whole matter with like-minded and experienced people.

Last but not least have a chat with some S13 drivers and see what issues and improvements they had/made with their setup.