Awakening a sleeping outboard
http://forums.iboats.com/showthread.php?t=158086
I used my old floor as a template. You should be able to on that one. For the open bow section you'll need to make one. I'd use cardboard or sheet pink/blue construction foam from Lowes. Gluvit is the sealer. That's a step I wish I'd done on mine.
I think we should see if we can run it first. If he didn't let gas sit in the carbs it just might not be gummed up too bad. The rollers and bunks on that trailer will need work pretty quick. I don't know your water access situation but my family has a cabin on the Susquehanna down in Delta, PA with a ramp at the end of the street. If you needed to float the boat and have a place to tie it up and a place to work on the trailer we could certainly utilize that. See how I've shoved my way right into your project?