Anything else I should pay attention to?

If it's chrome finish, it's probably a non-T* coated lens. This might result
in low contrast or flare problems in certain light,

A thing to remember about C lenses:

These are the lenses Hasselblad made their reputation with. True, later
lenses have improvements but C lenses- in good condition- are nothing
to sneeze at!

but it certainly means
you've got a pretty old lens that may wll need servicing. I understand parts
are only available from cannibalising old lenses.

Not yet. There are still plenty of parts available for C lenses. In
ten years, perhaps, parts will be hard to find but not now.

If it's black finish with
a B50 filter thread (i.e. the front filter thread is bayonet style and 50mm
across) it's the same as the previous lens but with T* multicoating. It has
the same issues with spares, but will probably at least be a little newer.
If it is neither of the above, then it's a newer lens. Other than parts,
there shouldn't me much quality difference.

Again, parts are not of concern yet. Another thing to remember is that
if an older lense is still in prime physical condition (EX or better)
it probably has been amateur used whic means it hasn't had a lot of
usage cycles as compared with a professional used lens. A 30 year old
pro lense is going to be pretty beat up, although it also could be in
great shape because it has been rebuilt frequently.

Jeff