Pat, About the Calliope engine, it was Ford's attempt to build a competitive Group 7 car for CanAm competition. Having been at KarKraft at the time, I pretty much know the story. The Calliope three-valve engine is shown in the accompanying pix. Trans is a C-6 automatic combined with a 9-inch final drive in one case, thus an automatic transaxle. The fuel-injected engine had dual cams in the block! Chassis was from the Mk IV GT-40.
Ford decided to turn the car over to the Agepough (spl?) brothers, who didn't have the necessary resources (money) to campaign the car successfully against the Lolas and McLarens. It was too heavy and the engine wasn't fully developed, so a 429 was installed in its place, thus becoming the 429er. It didn't do a whole lot better.
Check out this web site for the restored Honker:
http://www.surreymotorsports.com/restore/honk.asp
As for a description of the engine and why it was developed, here's another web site to look at:
http://phystutor.tripod.com/stang/engines/exotics.html