I'd be very interested to hear too - Since most, if not all, of BOACs 707-336C "Cargo" freighters could be, and often were, converted to pax duty if the schedule called, the galleys were likely the same as the rest of the fleet - happy to be corrected! Was it always a male steward on the freighters or would Stewardesses fly too?
Until recently Qantas used to fly 767 night freighter flights to New Zealand (granted they were pax aircraft just operating cargo duty) and a single FA was onboard to arm/disarm doors, heat meals etc - so perhaps it is reasonably common for Cabin Crew to fly on freighter services.