This is the first Enya I've ever owned, and I haven't run it yet! So I don't know nothin' about Enya's specifically. I was always skeered off by the Importer. I had enough agony with World Engines "support" for my (many) Super Tigres to last me for decades. Looks like we'll be good with Enya, finally! Yaaaaaaaaaaaaayyyyyyyyyy!
It does seem strange that the heads would swap from a ST .46 onto an Enya .45, but remembering that these are Metric engines, bores and strokes are pretty standard. Bolt circles are likely to be even numbers. Considering that the bores may be within a few thou, the flange OD, could easily be similar, requiring the bolt circles to be similar. Since I have a new ST .46, I might have to take a gander at these pieces and see if I can duplicate Joe Supercool's tests.
Steve