I forgot to mention low operating costs as a requirement, but then that doesn't necessarily apply to old banged up PA31s.
90 with Avgas, do you mean the Orenda conversion or is there another?
I don't necessarily want Avgas, I was thinking more along the lines of a diesel PA31 derivative if anyone cares to develop it.
What about costs of running a Kingair 90 versus a Navajo/chieftain - are they actually comparable? I always believed the TPs would be alot more expensive and the Beech in general.