The supported crank made me hit the "buy now" button, and I think I see possibilities to even support the cams in a similar way.
The idea is to repurpose the (positive displacement) cooling pump to lubricate the cams. Oil supply the same way, by means of fuel/oil mix and seepage past the rings, the pump drawing an oil/air mix from the oil discharge point , that mist being blown into the camboxes mist-lubricating the cams, rockers and valves, and draining back to the sump, very similar to what I do with my airplane engines, only a different way of generating the oilmist. The seepage past the rings keeping the oil pan "full", and a slightly higher oil discharge point added.
The cooling water circulation is way too low. Going by what I saw in the vid, that is maybe 500 ml/minute, which at full chat would result in a delta-T of well over 50 degrees. That is unacceptable given that in the original design the cold water enters the right bank, heats up 25 degrees then enters the left bank. I cannot help but thinking that a warping engine block is inevitable. The idea is to mount a belt driven centrifugal pump somewhere and fit way larger in and outlet ports, feed the banks in parallel and try to keep the delta-T limited to maybe 10 degrees or so.

Right now, my ideas wander in the direction of a boat, probably with a closed circulation and bilge-cooling, and a "thermostat" function programmed in the TX over telemetry. The idea is to circulate from tank to pump via the bilgecooling, with a controllable bypass of the bilge cooling, over the engine and back to the tank. Measuring the return temperature, and have the bypass valve open or close proportionally on a return temperature of 80 (bypass fully closed) to 85 deg C (fully open). That should lower the inlet temperature of the cooling water accordingly and result in an average and "constant" engine temperature of 80 deg C. I could try to create some sort of thermostatic element, but those are slower in response than a temp probe and a servo and the engine is in its final installation anyway never going to run without TX/RX and functional telemetry, so I am not that worried about that. A failsafe can open the temperature control valve to full in case of loss of signal.
Not sure yet about the bilge cooling as the boat probably is going to be rather quick and bilge cooling gets vulnerable with increasing speeds. It could also be an internal heat exchanger fed with outboard water via a pick-up. Also not yet decided on a reversing gear or permanent drive. I do have a Controllable pitch propeller, but that one is nowhere near suitable for the power I expect.

But that is all rather premature, to be honest, I first have to have both hull and engine in my hands, then see what (if any) of the above is actually going to be possible.... Probably going to be a wild ride...