1970 340/727

The difference is, if it is stuck tightly, it could have a cracked cylinder or more from rust and water. If it turns at all, it has a better chance of not being a $1500 pile of scrap metal. That's the difference. I'm glad of your past experiences, but that speaks nothing about this particular engine.
There is still good antifreeze in the block so it isn’t cracked due to freezing,