I don't see the point of bulding your car up with an AT then driving it, THEN switching to a 5-speed.
Not only would it make it more complicated tuning-wise, but it would be a big inconvenience to have to take parts of the engine apart in which you could have already had apart the first time you were modifying it.
I have a 5-speed D16z6 and i can drive like a grandma all day long.
Just control yourself and you wont find yourself drifting through instersections at 2am

..
why wear the tranny and keep replacing clutches and throw out bearings
EDIT: Also my clutch
supposedly lasted the whole life of my car until it was changed out in 2002, its a 93 with 260,000ish miles, the idea was the older man and woman that had it before me, drove it SLOW. You can do this too my lacking in pressure applied to the pedal that actuates gas flow, QUITE a simple process mind you!
And i'm sorry you had a mustang