Kind of stuck between a rock and a hard place here, since the cost of the repair is about equal to the value of the car......so it doesn't seem to make much sense to repair it.....in fact, value of the car could be lower(or higher) depending on the condition of the interior, exterior(you said you need a W/S, that is usually covered under car insurance around here), tires, transmission, etc.
Couldn't hurt to try to retorque the bolts(upper plenum would have to be removed) and then use the GM tablets(they have to crushed and put into the cooling system).....
GTP Dad, $60/hr? No shop I know would do it for that.....maybe under the table?