After my usual excessive amount of deliberation, consultation and faffing about I'm pleased to announce that I am now an M-F'er. (Many people say that I've been one for years, but they're just being mean...! :) )
I have today received through the post a Mamiya C330S with an 80mm f2.8 Sekor S lens. Condition appears good with merely a little paint missing, the flash mode switch araldited into the 'X' position (er, why?!?!?!?! Doesn't bother me, anyway.) and a little play in the aperture ring (which I can work around). Bellows appear light-tight, light seals look in good nick, the lenses are bright and unmarked and the shutter sounds okay.
It's on approval so it'll get a trial run on the way home and I'll have a darkroom session over the weekend (any excuse!) to assess it. (If it doesn't work I can always drive nails with it!)
Thanks to everyone who's provided advice and information during my (over-long, as usual!) run up to this purchase.
All the best,