Sure, that's a good deal. I bought Matt Miller's D-II, and I've been picking up extras for it like neg carriers and lens cones off eBay for cheap.

The original D-II came with only a 4x5" condensor which was and can be used with all formats, but it's possible to get other condensor sets optimized for smaller formats. The only downside to using the 4x5" condensor for everything is you lose some efficiency with the smaller formats, but it works.

Use a flat lensboard for 50-105mm, the 2-1/2" cone for 135mm, and the 4-1/2" cone for 150mm. I have a spare 2-1/2" cone that I'd be willing to sell, if you need one. You can also get parts and lots of info from

Enlarging lenses are so cheap these days, I'd stick to modern 6-element designs like Schneider Componon-S, Rodagon, or the 6-element EL-Nikkors (or the Apo-Componon and Apo-Rodagon, if you have the budget). You should be able to get a decent 50/2.8 for around $50, and maybe $80-125 for a modern 135mm or 150mm.