In the united states it makes absolutely no sense to mod an RB26dett transmission to fit due to lack of availability. If you happen to need another trans for some reason they are not all that easy to find.
I have a z32 trans in my car, but mines an S14.
Do what you want, but when making your decision remember that your creating a setup based on a transmission that you can't call a salvage yard for.
Good luck!
Evan
BTW, search google for the images. Its been along time since I saw those pictures.