Are you certain the sight is symmetric?
Cant caused by the dovetail can be fixed with a file, and in not much time. I would use a #2 cut Swiss pillar file, a safe edge dovetail file, a bunch of tape, and a vise with clean soft jaws.
Working the dovetail and the sight together is typical and about the only way to avoid a giant gap under the front sight blade.
A slightly too loose fit can be tightened by peening the dovetail floor. And loktite is a standard in the front sight.
The dovetail should be asymmetric if it's the problem. Look down on the sight, the high side will be narrower than the low side.
Removing the sight the bottom of the dovetail can be checked with an accurate square to find out if it's out of whack in the roll axis (parallel to the barrel centerline).