Ok, i've decided to use a small motorbike engine as an inboard. I think i've watched too many episodes of junkyard wars / scrapheap challenge. But it'll be awesome, and outboards are just too expensive.
So, for the grand total of $140, i got this, it's a 1986ish BR250 Kawasaki:

Next up, i ripped off all the wiring and rewired it, because it wouldn't spark. Used the service manual for a KLX250, was 99% the same wiring:

And so I am currently fighting with the carby: