Bob - are you trying to move into the "rice burner" class of Corvette. Is this your next Vette? Or a job.  (Rice burner = those cars manufactured in Asia that all look the same except for little bits stolen from marque names ).
Mate
There is no denying the later model vettes have better suspension geometry.
The C3 has a tendency  to to become unstable under power  driving out  of corners.
360s  comes to mind.
a better rear set up and a pair of 325's under the arse end may make a difference
So I'm filling  what spare time I have, with another project .
and then  the Chassis
one problem that is very difficult to get around is the Chassis. Its going to bend no mater what is done.
 keeping all 4 wheels  firmly planted is a well, mmm, a problem to be overcome
Time will tell if I'm wasting my  the efforts of not.
Bfit