Re: Building a more accurate Hi-Power
White Hawk, an old friend and fellow shooter, Armand Swenson, (you may want to google his name, or 'Swenson's .45 shop) often thought 'outside of the box', and simply said, "it needs a bushing".
His work on the Hi Power is easily distinguished by the presence of a 'screw in' barrel bushing; I never saw one leave the shop, without.
The mag disconnect is an easy thing to lose, but the trigger still works up thru the frame, back, thru the slide, then down, thru the frame, serving as the disconnector, as well.
Every piece in the chain needs to be inspected, polished, geometry checked, if you want that 3# 'Colt ' trigger.
Bar-Sto Machine used to manufacture barrels, excellent ones, both 'drop in', and for fitting, to the pistol.
Hope this gives you some ideas.
Don't start no s**t and there won't be none, Terry