I suggest looking at a couple of 1911 specialty boards. Stickies on a couple of those will answer many questions.
The most immediate issue is the question of collet bushings. Collet bushings work well but Colt adopted collet bushings to save money on fitting then failed to check clearance on the collet bushing as the bushing fingers move in and out. Improperly fitted the collet bushing will eventually break and lock up the pistol. For this reason many will have been replaced long ago. With proper clearance there is no urgency about making any changes.
Colt rimfire conversions, in modern usage usually called Service Ace, are notoriously finicky about loads despite the floating chamber to accelerate the slide. The common late production has an Acro sight that can be replaced with an Eliason or other target sights. An earlier Service Ace has a higher mounted adjustable sight. Magazines that actually work for rimfire in the genuine 1911 are few and far between and pricey as such things go. Parts are often missing especially the rim fire slide stop with a #2 marking as owners mixed and matched parts.
I have no idea what a fair price might be and these inflationary days I wouldn't try to guess.
