I should have gotten a photo / video of the ICE in the engine compartment before I started ... but when I took it out I didn't know at the time I was going this route.
But here it is out of the boat, the 67 lb stinkpot:
(shown in the same orientation as the diagram in post #1)
Coincidentally, the entire engine is almost the exact same weight as
one 6 volt golf cart battery.
Which always drives home to me how much power there is in petroleum fuel...
.