Tried to replace my stock petcock with a Golan this afternoon. No go. It wouldn't fit all the way up into the tank with the screen filter in place. Worked fine after I removed the screen, but I didn't have an in-line fuel filter on hand and it was too late to run to a store to get one, so the stocker is back in it.

Wasted part of an afternoon.
If, when you removed the stock petcock, the screen stayed in the tank, you most certainly would have difficulty trying to insert a different petcock.
There has been no difficulty, ever reported, regarding replacing the stock petcock with an aftermarket unit.
I think that was your problem.
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