Thanks Richard, I came across your (sweet!) bike today; no bottom cooling fins on mine, so the verdict is in; I do not have a Webco head (insert sad trombone 'wah, wah, wahhh' here).

My Ace100B also came with a compression release in the head.. I was under the impression that it's a Webco high compression head, as it appears to look identical to one, though I don't see a WEBCO stamping near the plug holes as I've seen in photos.. Assumed it was due to lack of room. Wishful think...