It depends on the location of the freeze plug. If the problem really is just a freeze plug it should be already out of the block. Find the open hole. If it's accessable put a rubber temporary plug in it and fill up the cooling system and check for leaks in the block.
Like Proffit says,it probably has a busted block. Fifty year old freeze plugs have usually taken root and don't push out as designed.
Your 4-speed has a granny gear low, as you guessed for "stump pulling". In normal driving you would start in 2nd.
