Thanks for posting those! I've updated the main pic of the Cosmic Swirl.
The case is actually a UM150C. The U obviously means USA Custom and the only difference is the plaque on the front. That would be the correct case from 1990-92, but it would just be an RG550C in 1989.
From 1990-94, Ibanez offered the M100C, M150C and UM150C, which are all effectively the same case. This is what I believe the differences are.
M100C - Professional Deluxe plaque, black interior, black twist latches. Case for RG400/500.
M150C - Prestige Deluxe plaque, grey interior, silver twist latches. Case for RG700, Roadstar Pro, JS
, RBM, etc.
UM150C - U.S.A. Custom plaque, grey interior, silver twist latches. Case for USA Customs.
Starting in 1995, there was only the M100C. These have a black interior and buckle-style latches.