There's a Certified 914 operators manual
here , this gives a MTOP of 84.5kW / 5,800 RPM / 114 hp, and an MCP of 73.5kW / 5,500 RPM / 100 hp. It doesn't say so, but I think that Rotax normally follow the general convention of MTOP as 5 minute power.
I've sat through a few presentations by Mark Wilksch, who knows a thing or two about diesels in flying machines. He's of the view that below about 120hp
in a fixed wing a Diesel cannot compete on power:weight with a good 4-stroke SI engine such as the 912/914. I'd venture that because of the rather higher continuous power (and thus fuel consumption) requirements of a helicopter, that threshold power is going to increase. That said, if you are looking for a Diesel,
the WAM 160 might be a good starting point.
G