Thanks for the information and the advice. I was thinking the same thing, about connecting it up to the tractor before buying it, though the mower is 20 miles away, and I don't have a trailer to get the tractor there. It will be up to the seller if he is willing for the mower to be brought to the tractor to be tried out before being purchased.
Here's a photo of the model of the mower. The model was first manufactured in 1968. The tractor in the picture looks to me like what would be a compact tractor today. Looks about the size of a Ford 30 HP.
The one I am looking at is weathered, but the seller has been using it and says it works fine. It looks to be in functional condition.