Quote Originally Posted by lilserenity View Post
The issue isn't so much the lens thread size as that is fine, it's the lens board's convex/concave design is just curved a little too much and the lens is fatter than the diameter of the convex section of the lens board, meaning I can push the lens far up enough to get it to screw in.
Ah, I see what you problem is.

I've never seen a flat lensboard for these enlargers. I'm using a Hanza 50mm 2.8 (which despite its odd name is a very good lens), and it fits in the lensboard that you have. Alternatively, you can try find a Meopta lens, an Anaret for example, which is a four element tessar design. The Anaret 80mm I have is very sharp.