Not a lot, to be honest. Generally poorly routed, overly heavy and chances are you're going to have to butcher your neck or the body to convert three bolt system to four or vice-versa.
A refin will affect the value for sure, but since it's just the body you're not exactly dealing with an all-original specimen anyway, but there's no hard and fast rules when it comes to the value of old Fenders, seemingly anything goes.
Honestly, I don't want to poo-poo on your parade but I'm mystified why anyone would actively seek out a body from that era. I used to have a 70's J and the pickup routes were frankly embarassing, I would also recommend you test whatever neck you're planning on using for neck pocket fit before you purchase, too, don't buy yourself a problem.