The MH models are the ones with feed levers more typical of production-style work. You know that, right? There's no automatic table feed in X other than the hand lever, and Y is by lever handle as well I believe. I suppose there's still value in that, but not nearly as versatile as the "F" models that have table feed.
Correct. Except that the M1 through M1C was the basic model, where you move the table on any of the three axis's by turning a hand wheel or crank. The MF through MFC add power cross feed for the table drive. The MH through MHC has relatively fast acting levers for movement on the table cross feed and the table lift. Only the table IN/OUT has a hand wheel. Unless you have a specific need for that type of action, you will probably find it something that You'd rather not have.
It is of course convertible but will require quite a few major components,
If it should turn up again real cheap, it might be worth buying if the countershaft parts and maybe all of the guards are present. Those are parts that are frequently missing. If the next one that you consider buying isn't missing part of them, someone else soon will. And, assuming that they are present/intact, the back gears or the BG operating lever are frequently either missing or broken. As a gold donor, you can list items for sale in the various For Sale Fora.