looking for exhaust manifolds that will fit my 1967 firebird. It has a 400 w/edelbrock performer rpm round port heads...bought Ram Air Restoration round port factory headers and there is no way the will fit. No room between the steering box and head...jacked the engine up 3/4" and still wont fit...Any ideas on why they will not come close to fitting? Extra info...the front sub frame is from a 1968 camaro, so its a 68 camaro steering box...research made me believe the steering boxes were the same for camaros and firebirds...all info welcome...Id rather not run headers...but if I have to, I have not been able to find any round port shorty headers...