It’s currently vacant and we are considering selling, but the foundation will be an issue.  

The best thing you can do to prevent future foundation issues is installing gutters around the property to repel away from the foundation.

Does anyone have information if placing it on a permanent foundation will make sense from a long-term value standpoint?

Anybody have any experience with a heaving foundation in the center of a pier and beam house?   

Make sure its on a permanent foundation, has concrete pillars, skirting and axles removed and in some states require hurricane Tie downs. 

I have been told by a contractor that the foundation of the building is intact, so it does not need to be torn down but requires a "gut renovation down to the studs."

Quote from @Elliot Rosen: Use a licensed and bonded foundation company and keep the invoices, and disclose it to the buyer.

If I donated to the aids health foundation expecting it to go to aids care or research, I would be very disappointed with this use of the money. 

You can then take that plan to foundation companies and get bids for that work. 2.

The foundation was already approved, permitted and finaled years ago for a 3400 sf house, and its solid and I won't be building directly on the overhang edge; but rather back away from the edge a few feet to prevent any load issues all the weight will be on the longer sides of the existing footing.