Hammond Racing,
one thing to consider, what performance [et] will you be happy with?
For NHRA legal stockers the only reasonable combination for the 3rd generation [1982 - 1992] is the 305 four barrel setup. So find what et those cars run and is that acceptable to you.
The 350 Tuned Port is not a good choice, just a weak package because of the small throttle body and small, long runners.
Both first generation [1967 - 1969] and second generation [1970 - 1981] have a large choice of power plants and can be very fast with several different combinations. In addition, parts are easy, the combo is worked out, it can use Calvert suspension
and factory 12 bolt rear etc.
The 4th Gen is valid if you are ready for a fuel injection combo.
And a note about 3rd gen & 4th gen rear suspension. It requires and aftermarket rear housing and more rear suspension parts then a 1st or 2nd combo.
On the other hand, 4th gen bodies are cheap & plentiful where as a good core for a 2nd gen is becoming more and more expensive.
All food for thought.
Personally [just me because I am old and do not want the fuel injection learning curve] I would try to find a clean 2nd gen body then research the engine combos and performance that would make me happy.