How about just a little bit more info! Could start by what motor, what heads, what are the end results for performance you want, cam. Sorry but your post leaves a lot for guessing! Some people have five Mustangs so it's hard to tell in your profile which doen't indicate anything.
2015 Stage 3 Roush
'66' Ranchero w/almost done 302 T-5 swap
2000 4x4 Ranger
2003 4x2 Ranger
'69' Fairlane Cobra, 428 4-speed waiting for work