For $500 i would say it's worth a look, but sounds like there's no point if you don't have space for it. There are work-arounds to make up for the long head stock for general use. But it's still not an ideal lathe for "precision" gunsmithing.
I would be really careful in inspecting the gearing in the thing, both drive and all threading gears, cross slide, carriage, everything.
"ran when parked" is always iffy, especially if it's missing parts.