I have an 89 gt 5 speed convertable. My mods are a e303 cam, short shifter 3 inch exhaust, with no cats. The car has 72,ooo miles on it. Would I be better off rebuilding the motor to a 306 or should I get a crate motor? Or should i just mod what I have and if so where do I start? It is only a summer street driven car but looking for around 375-315 hp. Thanks I am new to mustangs and modding them. Thw car is lowered too