So lucky me, there was a shop locally that had the M3 and a variety of M2 and M4 bodies available. I tried the M3 and the 50 framelines are just too close to the edges, like the 40 were on the R3A. So while the view was gorgeous it was not appropriate, especially as with glasses I couldn't even see the 50 frame lines. So that wouldn't work with a 50 for me, let alone a 40.
On to the M2/4/4-2/4-P bodies that were available, and the 50 frame lines are just right. Plenty of space around them without glasses and just right with my glasses on. I tried it with the Voigtlander 40/1.4 and 35/1.2 (sadly no 40/1.2 in stock but that gave me a good idea of the size and handling) and various 50s. I think I'll go with a 40/1.4, the 1.2 is interesting but judging by the 35/1.2 it would be too big and intrusive in the finder.
So, I am now the proud owner of an M4 and will do a bit more thinking on whether I want a 40/1.4 or maybe a 50 Cron/Summarit/Nokton. Thank you all for the suggestions and opinions!