Hello looks like it might be a Marblehead, the Americans also have a rule of 50 / 800 i.e. 50 inches long and 800 square inches of sail. Very similar class. At over 80 years old I would get some advice from someone who can also see the boat before attempting work.
Personally I would not go down the lane of fibre glassing the insides. You can't go back to square one if you regret it. Varnish and stocking / tights material works well though.
I have a similar aged hull and probably like yours the planks are nailed in place. The wood will be very brittle especially if it is bare, I tried wetting the hull, it did help a bit but some carefully cut slivers of wood can help fill the cracks in the planking. I have to say I stopped doing my one, I was not clear on what outcome I wanted so she is back in storage.
So I suggest you work backwards what do you want her to be like when finished? Is it an ornament, a free sailing (Braine gear) yacht or radio control?
If you can work with wood great, but if not I would not start on this hull, sounds negative but ask Russell I often see him and there are other VMYG members who do this work. If you just want a sailing yacht you might want to trade it? There are a dwindling number of old pond yachts, best they are preserved properly.
I do a bit of restoration and have seen unwitting calamities performed on models yachts. A nicely done one can give a good financial return but it takes time and effort and expertise.
For you information the yacht would have had 3 sets of sails for different wind conditions, your boat has Braine sail and steering control. Lots of info on the Internet.
Best of luck.
Roy