Great looking rifle. May you have much luck with it inc. the trigger and scope.

You undoubtedly are familiar with the black max line of adhesives by Loctite. Some say it/they can work well to hold a scope that’s not too heavy. As an interim solution, you might try that and postpone the drilling and tapping, as the rifle is a classic the way it is without being D&T.

In any event, best of luck! I happen to have a grooved 521T and it is a real shooter, despite the clunky trigger.