Well, while I'm waiting for the dyno backlog to clear out, things are moving on.
Since the engine will be mounted about 4" higher than before, the headers will require some "lumps" in the engine cover for clearance. The stylized NACA ducts will disappear completely.
Since the original engine covers are of cored Kevlar/epoxy construction and fully painted, I didn't want to hack them up. I called Rex Jardine at Vector Powerboats, and it turns out that they still have a set of molds to make original "Mannerfelt"-style hatches. For a very reasonable price, they laid up a set of hatches with just the outer skins; no coring or inner skins. These will serve as the basis for a one-piece hatch, and make life much simpler than having to strip and cut up the original ones.
Still (as always), this process is inevitably going to involve more of the dreaded fiberglass dust...