I've owned a dozen Iver Johnson M1 carbines. I was fortunate enough to be aware of when Iver Johnson was going out of business after they'd moved to Jacksonville, Arkansas. I bought a number of Iver Johnson firearms at fire sale prices, including a number of carbines. Most of these would be the late production models and I can attest that they were of acceptable fit and finish and IJ parts were interchangable with USGI carbine parts. I took one mixmaster USGI Inland carbine I had and swapped all kinds of parts around with one of the IJ carbines and never had an issue with part interchangability or the function of the carbines with mixed USGI and IJ parts. The IJ receiver is not as good a quality as a USGI receiver, but the IJ is completely serviceable.
Although I have a good number of USGI carbines in my colleciton, I find I do a lot of shooting with an Iver Johnson and it's always the one I hand out when I take others to the range. I reload .30 carbine ammo and I've run hundreds of rounds through them without any more issues than one would have with a USGI carbine, and that's usually magazine issues.
Unlike some folks who poo-poo Iver Johnson carbines without any real hands on experiance, my experiance has been that they are an acceptably less expensive shooters than most USGI carbines these days. Oh, I much prefer USGI carbines like everyone else, and I probably would not have ever bought one (much less 12) If I'd not gotten them brand new on the cheap, but my experiance has not been the least bit negative with them as a functional firearm.
Here is the image of one of mine that's still new in the box that I bought about 20+ years ago.