So the choice, for CF, is 75x115mm (MR), 70x105mm (LR), or a custom size (eg, 75x105mm to match GO). I agree, I think the 65x105mm is likely too short.
The watch is ~44mm tall (spring bar to spring bar), for a total of 219mm with the LR strap or 234mm with the MR. My wrist is ~165mm, which gives a remainder 54mm on the LR and 69mm on the MR. Adjusting for strap thickness and the clasp, one might loose as much as 10mm, I would think, leaving 44mm and 59mm respectively. The first hole is usually about 12-13mm from the tip, and they are spaced about 5-6mm apart and 2mm across. Seven holes would run about 50mm long, or ~62mm from the tip. This is all guesstimating, but that makes me think either would be OK, but the LR a bit closer with a range of about ~155mm - 195mm while the MR was a tad long (170 - 210mm).
If those estimates are all correct, the minimum practical size of the standard 82x115mm GO strap is around 177mm. I would believe it, as that would set the minimum wrist just under 7", which is plausible.
That all makes sense, but I think I'll cut a piece of scrap to get my best possible estimate before ordering anything...