Now I have three

[painter777]

IS who made oilers and magazines was International Silver. After they got the OK to drop the Primary code.... I (for IS) I (for Inland)= II. They just marked IS afterward.
So a IS mag and oiler is fine for your RMC.
Here's a link to mag Id's: M1 Carbine 15 rnd Magazines

Here's a pic of a M2 trigger housing with the right wall cut away and left wall having the notch for a 9 spring. (I'm just trying to be sure your TH hasn't been modified,) I would expect your TH to be a narrow rear wall type II.
See here: The U.S. Caliber .30 Carbines - Trigger Housing Group


Your Frt sight is probably a TR, Look for a marking on your L flip leaf. Common staking by RMC......... Well, just look at these pics.

I think I found what you'll need. If not I'll follow up this weekend.