head gasket/coolant causing other issues?

[wagonist]

So I've got a line on buying a 90 JDM GTII touring wagon.

It's been sitting for a while (last registered in 2011) and was bought by the current owner with head gasket/coolant issues.

 

It seems to start and run a bit with the green check connectors under the dash joined, but won't run otherwise.

 

It's run down and needs work (interior, panels) to fix, and I have a spider manifold engine to drop in it, but I'm worried about it maybe having other engine electrical issues. Or is it just because of the coolant that it wouldn't run (i think it's got almost none left)?