Just fiddling with a WW2 Junkers Jumo design, only produces the same problems that saw the Jumo development abandoned.
There's no way of building a substantially lighter weight, water-cooled, highly fuel efficient diesel, using the opposed piston design.
onetrack, do you consider that common rail injection, solenoid fuel injectors and electronic engine management are 'just fiddling'?
Diesel engines have won the Le Mans 24 hour race and produced VW Golfs with better performance thah the comparable petrol version, so why do you suggest that applying modern levels of monitoring and control, not to mention 70+ years worth of metallurgical and computerised finite element analysis advances to an opposed piston diesel engine won't bear fruit?