Whatever you do don't try to pull start that engine, I tried to pull start a 75 HP Evinrude on an old 59' model Lonestar I was redoing when the starter failed and nearly yanked my arm off from the recoil.
I'm assuming you have a clear title to this rig? If so, I think I'd first start at TPW to see what registration will cost. I left an old pontoon bowfishing boat sit unregistered for 3 years. They wanted me to pay all three years to re-register even though the rig hadn't moved. I took the motor and controls off and put on a flatbottom. The pontoon boat is still yard art!
@Littlefeather you could use those pontoons for outriggers on the old flatbottom, heck I bet you could put a lift that would pull a whale onboard. Wonder why the registration was retroactive