I have the 65 and 80mm lenses for the M7II...I do not have a problem seeing the framelines of the 65mm in the viewfinder, but I don't wear glasses. I will look again to check, but I think there is a fairly comfortable amount of room there. That said, if you can't see the 35mm framelines on the MP, that is pretty dramatic. Most people can't see the 28 framelines with glasses, but can see the 35's.
In any case, I got the 65mm for the M7II to get a more general wide angle, and I think it does well in this case. The 80mm is definitely versatile and reasonably wide, but I don't think it was a particularly good choice for the system when looked at as a whole. 80mm is not the normal lens for 6x7...it is the normal lens for 6x6. It is like a 40mm, not a 50mm if you are used to 35mm film. The Mamiya's biggest handicap is that it is difficult to fill the frame with someone's head and shoulders with any of the lenses. The 150mm only focuses to 1.8m and the 80mm is too short even at 1m.
Here is an example of the 80mm at 1m:
It is still a bit too wide for most portraits. If it were a 105 that could focus to 1m, it would be much better in this sense. But the Mamiya RF probably does not have the baselength for that.
ANYWAY, sorry for that huge digression. Basically, if you want something that feels like a wide 35mm lens or a narrow 28mm lens, get the 65mm. If you want something that feels like a tight 35mm lens or a 40mm lens, get the 80mm. Both are equally good, though the 80mm is a little smaller.
65mm:
80mm: