I'd take good eyesight over custom fitting any day of the week.

When I was a young'un I could shoot at and hit just about anything within reach of the gun, and it didn't matter what the gun's dimensions were. I am one of the humans who was born with arms that bend at both the elbow and shoulder and a neck that can move a few degrees. That always did, and still does, take care of the gun fit issues. What I don't have now are eyes that can put it all together.