That's incorrect. The G-3 should never used the R1. It could probably hold it, as the 190G was based off the 190A5 wing. It was for A5s, A6s, and A8s. 190G models were designed for long-range bomber duties (hence the drop tanks).
I would very much love the R1 kit, and have asked for it for a while now.
The 190a5 skin for JG11 that I made is from a pilot named Hondt. [Edit: White tail, red stripe heading toward nose] It's supposed to have the R1 kit (6x20mm total), but it's not modeled in this game. (Yet?)