Newb with lots of questions

[skinnysfd]

posted in the wrong section earlier so here it is:
Alright guys heres the deal... I have a 1970 gmc pictured below and want to set it up for drag raceing 1/4 mile. so far my best time has been 14.05 and i know i have around 3:11 or so gearing in the rear end. it also a one wheel wonder. i have the motor built as well as a built tranny in it. the motor has been dyno'd at 400-450 hp motor alone . now i want to run in the low to mid 11's for starters and go from there. i have a 100 shot nitrous avaliable and am running only a 2200 stall convertor right now. so im thinking going with a 3200 stall ( because motors dyno sheet showed 3500-6200 is the power range) and putting in a different rear end with different gearing. so my question is ... Am i on the right track in this thinking? If so whats the best gearing for these trucks and what rearend? ford 9", chevy 12 bolt??? also wondering if i should go 4:11 or 4:55 whats yalls experience and any other advice is welcome and needed. Also going to be putting fuel tank in the bed as well and getting it out of the cab. was also thinking a 2" front drop and 4" rear drop???