I would take a close look at that gun. The sight rib on the top looks interesting. Do you have a pic of the top of the slide? When it's field stripped are there any stampings or initials inside? Any under the stocks?
The gun was subject to some abuse. A professional may have started the work and Bubba kept at it. Hard to say without a close look.
On the squared trigger guard...in the late 70s and 80s a European technique of competitive shooters of placing the index finger of the support hand at the front of the trigger guard "jumped the pond" as they say. Swenson did a lot of this work on 1911s as others have mentioned. Jim Clark did some too he also just knurled the front of the trigger guard on 1911s.
Gun manufacturers took to this gimmick like crazy. S&W began squaring off the front of the trigger guards on their 2nd and third Gen guns. The CZ 75 went from a lovely oval trigger guard to a squared off one. H&K went to the style. When Glocks appeared they began with it, etc.
Old guns like this are interesting. They tell a story and can sometimes be brought back.