Tu answer a few of ur questions
1. a wheel tub is a part that replaces the rear wheel wells.
2. I think in application of ur sorts a quick change and roll cage are unnessary.
3. that car would prob do 110 to 130 stock so, 150- 160 with 351 ( estimate ).
4. ull need somtin better than a TK0 with 351.
5. I dont think top speed and acceleration can come in the same package but, I could be wrong
6. Never heard of a 60's stang blowin up unless, it was flipped with a ruptured tank.
7. 5-15 MPG probably
8. Flowmaster, Summit Turbo's, Dynomax all are nice sounding and can be loud depending on model of mulffler. Glasspack tube mufflers are just plain LOUD but, are by far the cheapest.