Hi and welcome to the site.

It's hard to say with those engines options what would be the best to go go for. The 4x4 engine is the better variant, but both of them sound like they need some money spent on them. Second hand Cossie engines are always a bit of an unknown quantity unless they come with the bills to prove, and even then there has to be an element of trust.

Personally, I'd buy whatever engine fits in your budget which still leaves you enough left over to rectify whatever might need replacing in a worst case scenario.