If you got a 225ci slant six this wouldn't be a problem. Get rid of the inferior V8. Otherwise, headers are naturally thinner than exhaust manifolds...which means they dissipate heat much more quickly...obviously you did not take this into your design...otherwise, I think it's funny how American "muscle" power these days do not tend to take practicality into design but think that bigger is better while missing the whole point. Good luck.