RE: Eager Beaver engine
I have two of those, my measurements gave 35cc also. One I got missing a good portion of the saw workings. the engines have roller bearings, so they're not the best airplane engine, not to mention the front carb setup... I stripped the saw down, removed the oil tank, cut off the oil pump workings (tapped the hole that was left to 1/4-20 and installed a short bolt sealed with silicone) and it's a little cleaner than what you have pictured
I figured I'd use it for a boat or car or something, my second engine is staying in it's configuration, it's a nifty little 7" chop saw, got that one for free too.
did yours have the clutch setup? that's one thing my engine came without, and if using it for a boat or car it would be kinda helpful... that is if you wouldn't mind parting with those parts...