definetly a wider tire in the rear with a narrower tire in the front, interco once told me run boggers on the rear where there isn't much weight and to run regular tsl up front for their flotation quality. and all the guys running the pit here run 10 bolts front and rear for ground clearance, and they are so common if you screw one off they just sling another one under it and put their spool and gears in it,
but with you wanting it to be road worthy also a full spool isn't a good idea, maybe have two rears one for the street and one for the pit and run a full spool in it, the day before unhook driveshaft block truck up in front of springs and undo your shackles and roll the rear out and put the race rear in, or like has already been posted make a race only truck.
alot of guys here run the vortec heads that except the perimeter valve cover and the old style intake so it looks more "stock" our rules allow for up to a 36" tire and as much lift as you want to run. they have a book to see what came stock and i run in the stock 6 cylinder class with a 74 k5 with 12 bolt rear and 10 bolt front, and a 98 vortec 4.3 with 35's just abou 2-3" wider in the rear with regular tsls up front, and i win quite a bit because not alot of competition in 6 banger class,
there are alot in the 4 and 8 hole classes, but very few in 6, and what is in my class are mostly 6 cylinder toyotas and inline six jeeps. you can do engine swaps and there is one cj5 that has me worried a little he has d44 front and rear and a 4.3 just like mine. i would like to put a powerglide in mine and try and pass it off as a th350, but i like playing by the rules becuse if you get caught cheating they ban you for good,
like this one guy that was dominating in the 8 cylinder stock class running a 350/350/203 but they caught him with a sneaky pete in the evaporator box and he ran his lines thru the heater hoses and tapped into the intake runner in the lifter valley. pretty ingenuise, but he can't play there ever again