I run an original 2-carb. Fenton intake with original Fenton headers and had to do some grinding. You would think Fenton and Fenton would bolt right up. Actually what helped the most was angle milling the header flanges where they bolt to the head, so the headers tipped in slightly and cleared the intake. I didn't want to angle mill the intake as the carbs should be level.
I have also had to mill off the heat riser flange more than once on a Offy intake to get it to fit a stock split exhaust. If there isn't enough material there, you will have to mill it down to get the flanges parallel and then make an aluminum spacer to fill the gap. The intake should fit the alignment rings and the exhaust should line up with the ports and end studs on the head when they are bolted to each other. Don't bolt the intake and exhaust together and then clamp them up with the intake on the rings and the exhaust all out of whack. Keep that exhaust flowing smooth!
