I used to own a 1976 PA 28-151 which is essentially the slightly newer version of the 140 you are looking at, I believe 1976 was the first year they dropped the "Hershey bar" wing of the 140 and went to the 151 model. As others have said its a 3 seater at a stretch, but does 2 people quite well. Its a good solid design and a great trainer. If I remember correctly RAM have an STC to take the Lyc 320 engine for that model from 150 to 160 HP without a lot of expense over what a straight overhaul would be.
I used to love the wing leveler in my warrior, wish I had it in the Maule.
Good luck