Hi all,
Thanks for your help. So I happened upon a treasure trove of a van being broken purely by chance (was going to pick up a swivel seat), condition of everything was an unknow so I spent 6 hours stripping out the fridge, sink, zig unit, and zig electrical control panel. '85 high top and unbelievably it still had the original TV and these insane slide out wine racks either side - camping in '80's style..
So far fridge cleaned up and tested via the zig unit and zig unit putting out good steady voltage and fridge cooling nicely! Just waiting on a regulator to test the gas with the fridge as a next step, flue etc. has been given a through cleanout and piezo spark working...
one step forwards

But will probably be posting more questions about how to hook it all together so I can get the zig unit powering the fridge while driving and essentially a leisure system up and running. I got most of the cabling out as it was to try and learn how they'd rigged it and trying to get my head around the instruction manuals I found online.
There was also a water pump, but that seems dead though replacements are pretty cheap on ebay.
Been a busy few days

Will most likely have some spare bits at the end which I'll post up on the forums...