Personally, I would not refinish this bow, or any other Jack Howards unless one is an expert at sanding the type of glass Jack used. The glass is prone to slivering and one can wreck the bow.
If it were me I'd leave the bow as is and just enjoy it. Those holes can be filled with epoxy and that place where an arrow holder was place can use just a couple coats of polyurethane.
Otherwise the bow looks to be in good shape. Am tryint to put together a list of serial numbers, specs and ownership of Jack Howard bows. Would you mind telling me what the serial number is on your 54# Gamemaster Jet?