Mild C4 build

I just got a C4 to swap in place of the manual 3 speed behind my 302 ('73 F-100). The truck is used as a daily driver and I go bracket racing maybe every few months. The 302 puts out about 300hp and I don't plan to go higher. I'm about to rebuild this C4 (a '73 model) but not as a race tranny. Still, I am looking for suggestions on improving reliability first, and getting better shifts second. What can you folks suggest? Thanks, Polkat