I have a frankensteined 84 GN with Vac brakes and a 87 GN motor. I read that a big cam will effect the vac brakes. My brakes were not great before the swap but i had a vac leak so i thought that was the problem. after the swap i still have pretty bad brakes and was wondering if the 221/221 cam is the reason. I also think it may be a weak mastercylinder. it is a reman from O'reilly's.