I'm not a designer and this is probably a stupid question, but couldn't you just bring the photo you have which looks to be a decent resolution into Illustrator and trace it, get a clean vector, size it, then drag it into photoshop and work some magic? I realize you lose the vectoring but if you bring it into PS at scale it should look great.
Good deals can be had on ebay for OEM decals, but not this time of year. Best of Luck.
Hey Pat, only Leisure boat owners suck, Fishing Boat owners are awesome though (most of us).