Ian11, my newest Series 80 is set up to my own personal preferences, and nothing wrong with what you are wanting to try, either. Some folks get themselves frustrated when they start cutting into the slide or frame, or "polish" parts to the point where they are seriously out of specifications for good function. Drop in parts are nice because if you don't like them, you can put the old part back! I personally like steel arched mainspring housings because they tend to balance a bit better in my hand, and I have long fingers, so the long trigger works well for me. I have used the Pach wraparounds for so long that a 45 feels funny to me with standard grips. I've had one set for so long that the diamonds molded into them are nearly worn smooth.
I have a couple of shooting star 8-round mags which stay loaded and have been that way for 10+ years, and they still work as they should. I have not tried the bevelled mag wells, but once again, I would think about the add on style, rather than having the frame sawed on. If your 1991 is of fairly recent manufacture, you will have the grooved feed ramp on the barrel. It seems to really help feeding lead loads, particularly the light 155 grain semi wadcutters. My older Series 80 needed some polishing to achieve reliability. The strides Colt has made to tighten their product is commendable!