[FredBMOC]

I have seen in person the coyote engined Backdraft and even got to see a little of the fabrication that was required to "shoehorn" the coyote engine in there. From what I saw, I believe that it's going to take a lot of work to get the coyote in the Kirkham. The coyote somehow seems to be a huge engine dimension wise and because it's a modern and emissions compliant engine you also need to get sensors to several different places including the exhausts; computer, etc so be prepared for a hefty premium being the first one with that engine.
Good luck on whatever direction you ultimately decide to go.