Tommy T-
Here we go again....only with two cylinders this time. Great! Can't wait for the rest.
Idea: Use two scaled up, "Hoglet" cylinders for a 60 degree V-Twin. Drawings for the "Hoglet"are easy to find. Or.....adapt a cylinder design from an air-cooled, radial, aero engine. If there is a crankcase a large diameter steel tube for the crankcase, and weld on two pieces of steel channel-iron, or square steel tubing, for the mounting flanges for the cylinders. The sides of the tubing can be cut with the same radius as the crankcase for a close fit. The channel iron/tube then can be welded to the crankcase at 60 or 90 degrees
So far this new build is starting off like your first engine. I see tapered roller bearings, and cut outs for balancing, in the two flywheels.
Because your engine builds are so informative, please note all the design changes that will use to make this engine lighter, a better quality, have less oil leaks, etc. To the experienced builders these changes might be obvious, but to me, with so little experience, it helps if changes are explained, and noted. It would be great if you can mention the dimensions of the major parts e.g. con-rod length, bore, stroke, etc.
Looking forward to seeing your progress.
Frank