I just bought a used Mamiya C330S camera w/80mm lens. All seems to be fairly straightforward, however I can't find where you set the film speed/ASA, and don't see it referenced in an online manual.
You can still find metered 'chimney' finders, though having used one I'd say stick to a regular light meter. BTW, congrats on the Mamiya purchase. Ace cameras as long as you don't rely on the distance scale!