I didn't have a month to watch it soak, so I used Ditzler Aircraft Stripper, which is an intense, methylene cloride based paint remover. Zip Strip is a more commonly available product that is usually sold in a jellied form. A yucky project, that will involve mutiple brush ons, and gentle scraping with a putty knife, until the plastic is removed from the wood. I took me about one afternoon and evening to get a stock clean, and I did soak it overnight, after the tough stuff was off, in acetone, which took the awful stain that was used off the wood. You will be handsomely rewarded with no loss in value if you get decent results with an oil type finish. Run-of-the-mill Berettas from that era are worth about what they are worth. Shooters, not collectors, per say. Up to about S3 grade, anyway.
The safe yearly exposure for adult, human sized animals to the above paint remover is right around zero-it's a heavy hitter carcinogen, so, protective stuff (gloves, organic vapor respirator, plenty of fresh air and a fan is a great idea) will keep you safe and sound.
Good luck, and let us know how it goes!
Ted