I swapped to manual steering to avoid that potential headache....Used to have 1&7/8" on the 451, swapping to 2" to see if it makes any difference. Yep it is a pump gas motor.

I've put 1&7/8 on another B body years ago with power steering and didn't have a problem, but it was a '72. Not sure if there's any difference there, always thought they were about the same. I'm thinking there's probably a tolerance stackup between the body and the headers, no two are really identical.....