I use a 23C and a 45MX. I use the 45 for all of my black and white. The 23C is set up for colour. I only shoot b&w in 4X5. Lensboards are interchangeable between the two. Also, the 4x4 lensboards are interchangeable with lensboards for my old speed graphic
If you buy a 23C or 45MX, I have quite a few 1/8" aluminum 4x4" sheets that I can bore on my metal lathe for lensboards. They may require a little filing to fit just right. The price is right. Free! Just let me know what the diameter of the threads are on your enlarger lens, and I'll bore the hole to that size. Pm me if you want me to make you one (or two).