440 B body manifold clearance

What "I" would try first would be the easiest. Loosen the bolts that hold the column seal adapter to the firewall and try prying the whole thing over to the driver's side and re-tighten. I've had success with that in the past. It doesn't look like you need much room.
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THIS WILL HELP! Youcould also turn down the coupler a few .000 , and slightly grind the rust off the manifold too. All 3 will probably do it !