I'll need the serial number off the rear dropout to be sure but this looks like a 1964 Monark El Camino, built by the Huffman corporation. Huffman bought out the struggling Monark Silver King Co in 1958 and built Huffy bicycles out of their plants under different trim and badging. These later Monarks are sometimes call "Huffarks" by some snooty collectors.
They're not especially valuable, in fact I'd say they're worth less than their Huffy-badged counterparts because most people don't remember any 1960's Monarks. They just weren't marketed very much. They're somewhat rare but the nostalgia isn't there to drive prices.
I own two of these later Monarks myself, a '61 Spartan and a '64 Silver King. They're cool, uncommon, and affordable. Unfortunately, finding original painted parts and decals is not easy. Your bike is far from original. I wouldn't worry about putting it back to stock, I'd enjoy it as it is.