Those diesel engines that are at an advanced stage of development are all, sensibly, designed to be of compatible mass and power output to established Lycoming and Contis, for obvious reasons.
I'm not very up to speed with how far they are along the certification line, but I believe that Aerospat. nee SOCATA are flying or about to fly one in the TB20.
It would appear that the 220hp plant will be first to be offered, then the 180ish then, I believe, a 300ish hp motor.
This should more or less cover the 172 and 206/207 a/c at least.
I guess diesel makes a lot of sense for MAF, given the presumed difficulties of obtaining AVGAS as opposed to AVTUR?