that diamiter should work fine. go to big and it will be slow to spool to small and it will restrict. that should be good though.
given the way the manifolds are held to the block you wanna measure the intake to see what that is and get a header flange to match. ive ran different size intake and header flanges and had to put a spacer in there because the triangle wouldnt hold both, just not enough room for it to sit on that much of an angle.
