Welcome mate,
That sucks about the dodgy bob seller. Unfortunately this is an all too familiar story many of us run into at one point or another. I once bought an outboard for my boat from "a 4th year apprentice marine mechanic" as I was getting it cheap I didn't bother to test it before buying. I get it home, got it running and water POURED out the thermostat housing. On closer inspection I found the dodgy ar#e hole had removed the thermostat (I assume it was jammed) and replaced the housing with NO gasket AND to make it worse the bolts had obviously sheared so he had drilled them out (On a terrible angle) and replaced with tec screws! Once I had fixed all that it was a good little engine but If I couldn't do the work myself it would have cost me an arm and a leg!
I really hate when people think it's OK to rip others off.
I can't help at all with your project but there are heaps of guys here that can/will.
Pete