Actually I peeked and Formby's appears for sale on Amazon. Quite pricey but available, $60 or so for a quart.

The previous owner many years ago may have used a 4" paintbrush to lacquer the wood with no regard to boarders. Most all of the upper, lower tang, triggers and skeleton butt-plate were ham handed with an uneven amber coating. In this case all of the added finish required removal so the boarders were of no concern. The checkering required many successive applications and wiping, while the stock really didn't have much original finish left and cleaned up pretty fast. If the checking boarders are important a jell stripper applied with an artists brush would work with prudence.

Our landfill has a recycling center and I occasionally visit to find ancient items of interest. Some items I have sourced are Watco Danish Oil, Linseed Oil, Tung Oil etc. The items are free of charge, only requiring a signature for removal. The supplies used for this Parker were all sourced from there through the years.