Engine won't crank - earth or more serious? Options

[euro914er]

Hi everyone,

I'm a new UK owner - circa 6 months - of a 1.8L, 1974 in chrome yellow. The car is ex west coast, then was imported into the UAE by its PO around 4 years ago. There it was stripped down, repainted and reupholstered. The engine was put back in, but never recommissioned. The PO then came back to the UK about 2 years but never got around to connecting everything back up - all the vac hoses were missing, fuel lines gone and lots of wires go nowhere. Well I've sorted all of this and a few weeks back I attempted to turn her over. I was met with a "click" and after a quick google, internet wisdom pointed towards the solenoid. This was replaced and now the click has turned into a thunk. Jacking the wheel up and putting it into fifth, I can just about get the wheel to turn 180 degrees before I reach a hard stop. Plugs are out and diesel has been poured into to each cylinder. BTW - some leaks out of one cylinder - should it be doing that?

I'm now at the limit of my knowledge - some posts suggest its an earth strap problem - others suggest something more serious such as a stuck valve. The drivers side valve cover is over and all looks normal (according to a colleague). The passenger side will be more tricky as its deeply buried.

So what does the collective feel should be my next move? I've resisted pulling out the engine but I have a feeling I'm head that way. As you can see, she's mint apart from a sick engine