Best mods for handling IMO

coilovers
area -six rose jointed lower adjustable arms
poly bushed rear end.
set of r888 or prada if on budget
15 inch wheels no bigger..
spring rates can be changed to dial in what you feel best..

300-325 front and 500 rears for track car can go harder...

A quaife diff if the power is there will help alot too..