Doubt if a TKO would handle the torque put out by a well built big block, if you go with a big block, better plan on using either a Top Loader 4 speed or a Doug Nash (now Richmond) 5 speed.

Quick changes are made for dirt tracking, they are very noisy on the street because of the straight cut spur gears and if you hook them up good with good working rear suspension and slicks the pinion bearing boss on the housing tends to break. Forget the quick change and use a Ford 9" rear end with a Detroit Locker.

Both nitrous and a supercharger are overkill, there comes a point where it's too much horsepower to hook up on the street.

A 67 Mustang is a uni-body car, it is going to take a 10 point cage, frame ties, and very good working suspension to make it work.

Cost??? With the parts you mentioned, and if you are able to do all the fabrication and build work yourself, at least $15,000. If you have to have it built at a reputable shop, it is going to be in the $30,000 to $50,000 range.