E85 is awesome, but if there's not enought stations near you it sucks. Sounds like your XPZ build will be awesome, nice list going.
If you already have 90's, just keep them. If not, I'd go to a dealership and get L76 springs.
For the trans, some people have trashed their modded stocker with a 3.4 setup. Others have gone tens of thousands of miles trouble free. It really depends on driving habits. Personally I think the shift kit, cooler and fresh fluid with a new filter should be good enough. Other than that I'd just get a rebuilt one if you think you need it.
You're welcome, and good luck.
On my phone so sorry if it's short but as far as my xpz goes I have everything besides a Trans is4 injectors rails everything lol
For the Trans no 4th at least? I ask because I hear how they go out
If You Cant Hear The Whine You're Too Far Behind...