Hello Thomas...
I have the R3a, and use it with an M-Rokkor 40mm f2.0 and I like it very much.
The R3a does lack the 35mm frame lines, 40mm is as wide as you can go without an external viewfinder.
The 40mm framelines are pretty far out to the outer edge of the finder and I find this a little bit annoying. Others say just ignore the 40mm framelines, and compose with the entire finder and I do find that works well past 18 feet.
I also have the Konica M-Hexanon 50mm f2.0 and it is a really fine lens. I consider the R3a to be the best 50 shooter out there, as others have said - 1:1 finder allows for both eye open, a handy feature in many situations. The 50mm has a comfortable amount of air around the framelines.
If you get the R3a, you won't regret it. It's a very fine machine and a real bargain to boot.
Add a quality 40 or 50 and I think you'll be a happy camper.
I love the R3a's Auto Exposure mode. My example does seem to meter a bit more accurately with the 40 than the 50. It tends to overexpose a bit with the 50mm, but well within the lattitude of color negative.