[volt-nuts] Fluke 5200A (and other) extender boards

I got several inquiries when I mentioned I did a 5200A extender cable. I didn't like my solution since it uses ribbon cables and there is +/- (300V?) on some of the slots which is pushing what a ribbon cable can do, although it did pass a test with a 1000V insulation tester. There is a guy on

[volt-nuts] Solartron (aka Schlumberger) 7081

I've been offered a Solartron 7081 8.5 digit meter, but are having difficulty finding out much about this. Is there any "official" place where these can be calibrated? As far as I can see from a search of Companies House https://beta.companieshouse.gov.uk/company/02858371 Solartron Instruments Lt