As important as the peeling and replacement of glass (which indicates significant blistering, which were farily deep, if they peeled it enough to require another layer or two of glass)--is how the boat was dryed out. Unfortunately many boats are just peeled, washed and re-laminated or epoxied--with out real drying--dehumidifiers inside and out, sealed outside with plastic, or with hot wash/vacuum bagging to get moisture out of the laminate.
The cabin sides and decks of these early GB were plwwood. The teak decks on GB are better than many, but if they look like replacement--then it will be a big job--not at all cheap. To do a really good job, you may have to replace the plywood and the teak (plus the glass which is over the plywood). Marine ply will run $50 to 75 a sheet (depending on thickness and transport). Teak decks: $2.50 a lineal foot for 7/16" thick, 1 5/8 wide or $18.50 a sq foot, plus $12 a tube for two part polysulfide (alternative is to set the decks in epoxy--and costs will be close to the same or slightly more). There are some synthetic "teaks" which might be an alternative.
Another option for the decks is to put a truck bedliner or Durabak over the teak decks--assuming that the sub deck is in reasonable shape.
Generally the rot under cabin windows can be taken care of by scarfing in new plywood--but you can not go back with teak vineer, so you will have to paint or wall paper....Older boats, even glass are a lot of work to restore, depending on how they were built. The engine hours (assuming that the engine was properly cared for--if it has been abused, then the relitatively low hours don't mean as much. The tanks are also a plus--how about gen set and other systems--often these boats have to have electroncis and other systems redone. We redid a 20 year old boat and had to to some signific rewiring. Copper tain't cheap these days...But with the Grand Banks--The restored boat will often bring a good price down the line.
I assume that this is the boat in Riverside NJ. Looking at the photos (which can be very deceptive)--the boat doesn't look too bad--but there is some rough work in the cribing for the new fuel tanks. That would make me a little suspicious about how well the entire replacement was done.. Teak needs redoing--but that is only a few weeks work.--I would worry more about the decks.
The Onan is probably origional--and may be near the end of its life, despite having been "overhauled". Look carefully, but at that price, it looks like the type of boat I would buy, if I was younger, and fix up, use and sell for at least what you have in it..assuming that you do the work yourself. Get a good survey and engine survey.