The general rule in the old days was that you could overpaint cellulose (as used on cars) with enamel (oil base exterior paint)), but not the other way round. Back then those were the choices if it was getting wet. Given its age, one or other of those is the likely finish.
If in doubt and not going back to bare wood and whatever else is under there, oil base enamel is the safe bet. Spray or brush is your choice and depends on your preferences. Good brush enamel applied with a good brush can give very good results, but either way, preparation is king.
I have used paint stripping gel on plastic and fibreglass items with good results. Since it was got from a general hardware store decorating department, it should be both effective and harmless on wood. What effect it might have on old glue on a model is anybody's guess, and depends on the glue involved.