It might work for both the upper and lower felt, as it is just 1/32 taller than one, and 1/32 shorter than the other. It’s hard to measure the thickness of felt to any accuracy, as it is so fuzzy!
Rebuilt keyboard with your felts, reinstalled and the Great manual is working and feels great. Not sure about velocity sensitive feature since MIDI is not hooked up yet. Just ordered felts for the other two manuals.