The info you've gotten on your query is correct to the extent of my knowledge. I would add a couple of points though. First point: Rick B's observation about the comparative numbers of the various models he's seen matches mine. Because of that your nickle plated 'I' series might be worth more than a Mk V, Mk VII or MC-1 to a serious collector. The Swenson thumb safety would detract from that, but it's something to keep in mind.

Second point, the longer mags will all fit, any mag that will fit a 1911 will fit, but all are vulnerable to upward pressure from the supporting hand lifting them above the normal position in the frame during recoil, causing frequent jams. I've seen other folks solder or glue small blocks of aluminum to the forward lip of the bottom plate to stop the upward movement just as the lip does in the gun it's designed for. The idea is to get the mag catch to just engage the notch, as that positions the feed lips correctly.

Before I forget, the Pachmyer grips could have been installed at the factory, as they often offered to ship the guns I got from them with Pachmyers.

Pat