This frame was made out of the same 7075 Alloy as current production. There is no need for any steel insert. HP anmo that is designed to feed in an autoloading pistol will work just fine.
Uh hu. In the last 40 years I can't tell you how many LWT Colt Commanders I have rebuilt from first year guns to modern Colt "enhanced" guns. Or how many nice old 2nd hand Colt LWTs that I have passed on when I jack the slide open and see a bright, white, polished feed ramp.
Cut the anodizing off the feed ramp and your comment on what will "work just fine" is not my experience. Caspian aluminum frames come with nothing on them..and why they offer ramp inserts. Kimber guns? They are anodized. As are Rugers (Ruger uses ramped barrels or inserts). But not all anodizing is the same, not all forgings are the same even if built from 7075 aluminum.
From what I have seen the worst thing you can do to a Colt aluminum frame is take the hard anodizing off them. Reason that is a bad idea is there isn't anything hard to go back on them easily. Most anodizing isn't Level III mil spec but II at best that is used mostly for color/cosmetics.
Coatings of moderate thickness 1.8 μm to 25 μm (0.00007" to 0.001")
are known as Type II in North America, as named by MIL-A-8625, while coatings thicker than 25 μm (0.001") are known as Type III, hardcoat, hard anodizing, or engineered anodizing. Very thin coatings similar to those produced by chromic anodizing are known as Type IIB."
Plated? Likely a 1980's rebuild. What was it plated with?
Typically guns that have had their anodizing removed are simply clear coated with spray paint. Or at best with a modern polymer finish (read paint). Still neither are good/hard enough to run any modern hollow point on the feed ramp of an aluminum 1911 frame long term. As I said HP ammo and original Colt steel mag followers will chew up the ramp. Robar's NP3 (nickel plate) is the best option I found for refinishing a Colt aluminum frame. And it isn't hard enough or thick enough to solve the ramp problem on a aluminum Commander. Plus it is expensive for $ and wait time. It also has a telling yellow cast/color to it. Most durable finish for a Colt aluminum is the original Level III industrial anodizing. Ramp inserts are the answer to the problem we are discussing. Ruger's new LWT Commander 45 comes with a ramp insert. Full ramped barrels are another way to solve the same problem but less reliable than the original Browning design.
OP's photo shows a nice gun that was rebuilt in a tasteful manner. He asked what the finish was. Having done a few I'd say brushed hard chrome on the slide and a bead blasted frame with no clear coat. Very typical of the date that gun was rebuilt by the parts used...likely a Vedecki trigger, Pachmayr grips. early '80's sights. Colt grip safety. If that is a chip on the chrome back, top, right side of the slide, the chrome shop wasn't very skilled.
Most have found that using ball ammo in a 1911 works just fine for any social occasion. Clint Smith has been advocating ball ammo in LWT Commanders as long as I can remember. I use to bristle over that some. I don't now. Any time you go outside the original 1911 design in a steel gun there are issues. Thankfully with a little common sense most can be over come simply by choice of the right ammo and mags.
It is a nice old Commander rebuilt in a tasteful manner. Not saying it is a bad gun just trying to answer the question on what the likely finish is and the ramifications of that finish. The LWT Commander shown below was done in a similar manner around 1999.