$5k obo is a very friendly price. I know Ratsun guys like buying cheap cars but I hate to see you sell yourself short on this. Maybe throw it up on ebay with a link to this thread in early March when tax returns start hitting and I think you'll be surprised.
Bringing this one back from the dead.... did you ever try this manifold and carb? I just came into possession of one and am wondering if it is worth pursuing.
They are probably a common locking lugnut. See if you can match them at the auto parts store and pick up the tool. Or you can do what the theives do and just bust off all the studs.