Well, after enlarging some reference photos and doing some measurements,....I scavenged various tiny parts and components that looked like they could be modified and cast in resin.
Then after making some cast parts, I cut up and assembled them into an engine block and added six cylinder heads with cylinders.
The first picture shows a highly modified engine block cast from an old 1/48th Cessna kit, cut up, recast and reassembled, with a single exhaust pipe and air cooled fan ring for size comparison to reference photos. This thing is tiny in 1/48th....
The second shows a "tack-glued" engine assembly to take some more measurements and test fit on the engine deck...(yeah, the cylinders don't exactly line up yet on each side...I'll need to fix that).