couple of c6 ??????

hello, im building a c6 for a 72 mustang and would like to make it pretty stout, the servo letter i have is a P so what stock servo is better to use other than the R servo? i know the R is the best but the cost alot of money..
also the forward drum only has 4 disc in it and the direct has 3 this is a big block transmission is that write? will they hold up to a stock built 351m? also what color modulator is best to use its a push in?
i have built lots of c4's and added clutches to the drums in them can you add to the c6 drums by taken out the cushin spring? better yet do you know of a website that has mods for a c6? o-ya is a 1978 modle c6
D8AP-FB-019125
PJD AP3 K5
the code break down says it was a police tranny-fleet!!! if that matters...
thanks for all your help..
randy