I bet a Farmall F12 wouldn't run very well, if at all on diesel.
According to Nebraska tests, it pulled 16.2hp on gasoline at 1.7gph... and 14.5hp on Kerosene at 1.5gph.
I wouldn't know if it'd run any different between Kerosene and #2 diesel, but my neighbor started his F12 on gasoline, and ran it on diesel all the time... because Kerosene was expensive, and for him, #2 diesel was substantially less. Most tractors prior to 1945 or so had 'tractor fuel' or 'distillate' as either a standard or optional feature. My '37 unstyled Allis WC has two tanks- a starting (gasoline) tank and a running (distillate) tank. It has shutters over the radiator to get the engine temp high enough to spark-ignite diesel. Off the top of my head, I don't recall the carbeurator (vaporizer) having anything special about it, aside from separate fuel source valves.
I took another look at the posted pictures, and it does look something like injector fittings, but the angle didn't really look like an injection pump. I see plumbing for the compressor unloader...
What I see, is intake on one side, looks like a governor shaft housing (like the Farmall) which would be connected to a throttle plate (on a carb)... and exhaust on the other, so cross-flow head, rocker cover (so OHV) and clearly a magneto... but no spark plugs... Anybody see anything I missed?
Oh- NOW I see it... to the left of the #1 exhaust port, I see the wire terminal, but no wire. The others must be obscured by gack.
For what it's worth, Ingersoll-Rand DID manufacture engines. Locomotive engines, big industrials... I would NOT be the least bit suprised if they built this... or even... but it on the block of some other engine, and just made their own conversion...