further thoughts to consider: the thermostat determines the minimum temp the system maintains, but a 350 is very unlikely to ever run lower than 180, probably more like 190-195, but that's with a 15 lb pressure cap, which is a bit much for the original rad even if it's in perfect condition ... you need to use at least a 7# cap, and it'd be a good idea to rig an overflow system as well
Bill
