[spacemanspif]

If you are tearing apart the cooling system make sure the flush the radiator backwards. If the previous owner used some stop leak it could have clogged the rad and might contribute to your over heating issue. Heater core should be back flushed as well. Both can be done without pulling the thermostat which you'd have to do to flush the block. All this is under the assumption that you are flushing with a garden hose and not using a rad flush type additive product. Congrats on the purchase!