why not a cheep 280z or zx,,,find a beat one,, dump the inj,, weld the diff,,, short heavy springs all 4 corners,,,wide 15" steel wheels lo unspring weight,,,sticky low profile tires,,,rear roll bar turned into cage,,, raceing seat and harness,,maybe a fuel cell,,, with a holesaw or plasma cuter can get the desired 50/50 weight,,, and a lot of fun!!
in my math can be built for 2800 to 3000 dollars