Hi well the st has a good brake and suspension set up. Would make a good starting point or cheap upgrade,
The st engine will work well with fly wheel, decat, exhaust cam pully, under drive kit. Remove aircon, remap. Weight strip, will give u a fast responsive st near 200 brake with good torque, might get more with race can injectors and fuel pump.dif. Then it gets pricey
But if you want more the 2l may be best bet, and add st bits like the down pipe, brakes,