Kitting suggestions (assuming R0, R5 are staying):

To elaborate further re: R1 Pause: if you aren't including numpad
00, then R1 Pause shouldn't be included either, as that particular 1800 layout option is even less common than numpad
00. Neither key is justified in a GMK base kit, imo.
Additionally, 1.25c space is currently missing from the spacebars kit and should be added.