tko 500 or tko 600

I have a 98 mustang gt and i need a new transmission i heard the tko's were good but dont know which one would be a good choice for me. I have the following mods
4.10 gears
pullies
trickflow upper intake
70mm tb
ram air
K&n air filter
centerforce clutch
flowmasters 40 series
2 1/2 " exhaust with x pipe no cats
centerforce clutch


I have some 99 gt pi heads intake manifold, shorty headers at home which were gona be installed soon until my tranny died. and i was gona get some comp cams before installing everything. <----- wont be installed till next spring due to money problems now.

Which would be the best tranny???????????

also do theses trannys use my clutch from the t45 which is a centerforce clutch

can my centerforce be used tho

anyone know which would be beter and i also want a aluminum fly wheel is that any good?