White smoke! Blown head gasket?
It sat for 34 years unstarted and has only run for an hour since that time. Let it run a while. Go get some ice cream in it a few times. Take it to the grocery store some. Put some miles on it where it's actually doing a little work. Don't just condemn it over an hour in 34 years. It's entirely possible it's burning out built up moisture in the exhaust.