You should first check out the Hypalon and make sure its not dry-rotted so you'll know whether the boat's even worth spending money on to get it in shape for next season.
I don't know where you are since you didn't put that info down on your post or profile but if you're in Denver you can call up a few of the local inflatable repair places like Down River Equipment, AAA Inflatables, or Inflatable Technologies and get estimates on the conversion.
Nothing in the world is more yielding and gentle than water. Yet it has no equal for conquering the resistant and tough. The flexible can overcome the unbending; the soft can overcome the hard. - Lao Tse