I have had great experience with Dr. Gas making me various pipes with requested offsets. They'll do slip fit reducers, ovalized, etc.
Also, when I measured my reducers with a level, I found they weren't perfectly square to the flange and was able to rotate them and pick up clearance.
69 RS Conv therapy program, Autogear M22, 8-pt cage, with a new 410! SOLD
New therapy program - 68 Coupe. Will be survivor exterior, modern underpinnings! SOLD
67 Belair with perfect floors, pinchwelds and firewall. Hmmm!