Yesterday I read through two very long threads here. What I noticed is that practically no-one stipulates whether they had or have the bike on the side-stand or on some kind of lift.
For the record: my V11 Le Mans, built in 2002, long tank, wrinkle paint on the motor, black gauges, was on a Becker lifter when I was looking at the front grease nipple situation. So the back wheel was off the ground, and the angle of the front uni-joint was as "open" as it can get without undoing screws. I had the feeling that I maybe could have got onto the front nipple. Grease gun has a straight connector, but a flexible hose. In the end, I decided not to pursue it. Taking out the wheel is a good idea anyway, as there are a couple of other things that would benefit from being looked at.
@docc, the collar in your photo doesn't seem to have any holes in the sides of it. Mine does, such that I could probably undo the pinch bolts without removing the collar.
I'll be in the garage later, and will try and measure the collar in situ, but don't really expect to see numbers different from what has already been quoted here.
A thought came to me: maybe the collar is the same, but Guzzi used a different nipple on earlier models compared to the later ones. I.e. they figured out it was a bastard to get to, and changed to a different nipple.