Thanks...

For the other posters above -- Running a hose through it will not remove the calcium, lime, scale, grease, and rust deposits in the radiator. It will only (at best) break loose some surface contaminents.
For that reason, it is necessary to have it hot-tanked professionally. Otherwise, it won't cool any better than it does now, and the stuff you broke loose may kill your water pump, as it's ingested through the motor after you re-install the radiator.

The best option, especially for something with that age, is to buy a new radiator, and pull a freeze-plug from the block, to drain the block. Then, flush the system with fresh distilled water until it runs clear. Replace the freeze plug with a new one, and proper sealant (if required.) Then fill the system with a fresh mix of antifreeze and distilled water. After running the vehicle long enough to warm it up, and mix the water and coolant, allow it to cool, and use a good, accurate meter to check the level of the antifreeze in the water. If you're in Minnesota, you may want a 50/50, or even a 70/30 antifreeze mix. In VA, you would likely suffice with a 30/70, as the odds of it getting more than 15 below are slim to none.....