Hmmm, should I be nice or competitive? OK I will be nice, Rethink the T-case. I can tell you that even with suspension and a 16v you will have a hard time without the low range option. I run the same size tires and found the power to be lacking. I could barley catch a 8 valve car that had a t-case on the straights. I put a T-case in for the next race and was able to catch and pass everyone within the 1st lap.
Also, test test test. It sucks to find the weakness of your car during the race. Mine was the axle(like yours) Although, it took quite a beating before it broke. I had won the 1st race, was in 1st place, and thought I would try to set a fast lap. A lot of full throttle over washboards and jumps, coupled with the t-case gears, is what led to my broken axle I think.
Anyway, just trying to pass what little experience I have along. Good luck and I look forward to the build. Don't forget to introduce your team and post a build thread in the Zukiworld Challenge section.http://www.zukiworld.com/forum/race-team-introductions-information/
As for the fuel cell and apparel, I got my Fuel cell from Summit(cheap shipping) and all my apparel from www.saferacer.com
Your rear differential will accept the older axles. This is what I did when the axle broke. I even changed over the brake backing plates to retain the newer style brakes. I do not think you will need the bigger 4 door brakes, my car stops very quick.