im going to buy an 87 non turbo supra and i was wondering if anyone knows of any good mods for autocross and mild track use.

I would go turbo instead of getting an N/a. you will regret it later. Next, post this in the preoper section. third, i would go with some cheap eiback springs, tokiko struts, some ebay strut bar, cheapo drilled/slotted rotors, get rid of the heavy rims, get an underdrive kit, and a 1 piece driveshaft and you might have a START.