Here is a thread I started years ago called 50 Diesel Mostly: Diesel .50s (mostly) as can clearly be seen, some were better conversions than others
The OS LA 65 below turned a Bolly Clubman 13.5 x 8 at 9,300, this head was made by A. J. Coholic in Canada
The PAW 60 turned the Bolly Clubman 13.5 x 8 at 7,500

The head on the Irvine 53 above was a Davis Diesel proof of concept head for our military to burn Jet-A in them, it Ran fine on Davis ABC mix., the 53 was the king of the 50 size engine. An Air Force guy came to our flying field at Fort Belvoir and was shocked that I had it.

A surprisingly powerful Diesel conversion, an OS LA 65

Disappointing Diesel, a PAW 60