(The) World's Aircraft Engines in "Aerosphere 1939" (author Glenn D. Angle) has information (under manufacturer C-K-D) on the 'Praga' ESV and ESVR engines . The gear reduction model ESVR was rated at 650 HP @ 2100 rpm, bore and stroke 140 x 170mm, weight 1116 pounds. No information on a more powerful or larger version.
A 'reprint' of the engine section from Aerosphere 1939 is available on a CD from Weak Force Press, Huntsville, AL. It is highly recommended for anyone interested in aircraft engines. It is a great historic work with information on a staggering number of aircraft engines from the beginning of flight to the date of publication.