Nikon F100 eyepiece correction lenses and eyecups will fit the 6x7. Also, eyecups designed for the 67ii.
Good quality eyecups can be fetched from fleabay for around 16 ex ChinaLand; the dealer I use had them made specifically for him in a factory because he, like so many others, was incensed at the extreme price being charged at retail. I have seen Pentax OEM eyecups being sold for around $70 at J&JVENCKUS on FleaBay — that pair are serial offenders who never modify the extreme postage no matter what the size of it is you are buying.

The camera looks in good knick, with typical brassing from a well-used body. Just beware of the presence of the huge shutter curtain when drawing the leader across from a roll of new film; all too easy to press on the curtain...