Cluster Master problems or something else (amongst others!)

[Korgull]

Hi
First post - desperate owner trying to get van ready for summer.
I have a 1988 DG 1.9 WBX (new recon engine from Campershack) and have just installed it I'm discovering a host of electrical issues.

I've never had an oil pressure warning light or coolant warning light - I just very naively assumed all was good if it didn't light up - I now know the error of my ways. 
Having fitted the engine - bled the system etc the temp gauge seemed to be running high - above 3/4. Checked the fan by shorting across switch connector, low speed fine, high speed - nothing. Replaced the switch, now low speed comes on when engine hot - but still at 3/4 on gauge. Then through FB help discovered lack of relay for high speed - got one  fitted it and now it will work when shorting system. Ran the engine with fan switch off to force warning light to come on - no luck (checked in expansion tank and prongs seem clean and no light at ignition on either). ON the plus side, when I plugged the fan switch back in with hot engine the high speed kicked in - so that works.


Back behind the dashboard I discovered I had a Cluster Master fitted to replace PCB ribbon. BUT - the blue/black oil pressure sensor wire had been cut and connected to a broken LED, other end to ignition. So maybe someone already had issue and tried work around. I can't get the Oil Pressure LED to light up in any circumstance.  

Tried to check the CLuster Master wiring as there are 2 non connected wires one near speedo with pin coonector and the other - one I'm almost certain is Temp Led earth as there isn't anything on the centre pin and it had a ring connector - but putting on there did nothing. Unfortunately the wee paper labels with wire letters for location have faded so I'm in the dark with checking everthing is where it should be using the cluster master instructions.
I've checked various voltages at cluster master and can offer them if useful, and restistances across temp and fuel gauge - (both 50ohms)

As extra bonuses fuel gauge not working - though previous owner said had just had new sender fitted - so maybe an issue there - wrong way round / bad earth?.
And the PCB poking out the back of the hand brake / brake fluid warning has been snapped and is in the connector also dangling in the guts of the dashboard. 

I'm wondering if this is all a Cluster Master issue (not the brake warnings!) - and changing it for a Slaughter House or equivalent is the way forwards? Or am I looking at a dodgy temp gauge and cluster master? 

Anyone have any thoughts, advice as am tearing my hair out and want to solve this in a logical way - 

Cheers 
Andrew