Car is comming along nicly. Some advice from my experience with rear gearing. I had 3.91s installed in the rear of my 3100 # duster. When I installed the TKO-500 1st gear was way too low. I changed to 3.23s and lauches and drives extremly well with a 422ci small block,aluminum flywheel, corvette C/F dual friction clutch. I know its not a drag car NOR is mine. I found the lower gear just went to waste in useless rpm,tire smoke and shifts came too quickly. With your engine you will likely come to the same conclusion. I guess what I am saying is to just keep your eyes open for 3.55s or 3.23s. Trans ratios I found apply to my TKO-500 and your T56. I think 3.55s will be your prefered gear when you get to drive it.
Oh my rear tires are 275 60 15 bfg drag T/As pretty tall and they work fairly good for the corners.
Ratios:
TKO-500 (standard ratio) 3.27, 1.98, 1.34, 1.0, 0.68 I had my OD changed to the.82.

'98-02 F-body LS1 450tq. ratios 2.66 1.78 1.30 1.00 .74 .50 2.90
Good luck.