After much deliberation, I concluded that the cowl just really let the whole aircraft down. The way it had been butchered with all the screw holes, and how they sat perfectly at eye-level, proudly displaying a total disregard for craftsmanship... It was just garbage.
I figured, given how much time I've been working on this thing, the only way was The Right Way. So I bought some fiberglass supplies and got to work.
On the bottom of the lower cowling were two exit holes for some home-made exhaust system. The aircraft has a Vetterman system on it now, and these had since been covered with aluminum plate. You couldn't see them when the aircraft was parked, but I knew they were there and didn't like it.
I took two pieces of cardboard, rubbed them with wax, and taped them over the holes.
Then I laid upfour layers of bid on the inside.
Once dry, I skimmed the outside with flox paste, block sanded it down, skimmed it with a thin film of body filler, then blocked it from 40 through to 320 grit.
On the front end, I added back the screw tabs that had been cut off, and filled the dozen or so screw holes with flox.
I also added in the outer tabs that Bruce had suggested in his earlier post. To get the shape right, I joined the halves together and worked inside the cowl, brushing on melted wax (from a blue birthday candle) to stop the epoxy sticking to the lower cowl.
Then I began fettling the gaps. My day job is photographing stuff for car manufacturers, so I am slightly neurotic about shut lines and reflection lines in vehicles.
Several years ago I restored a '68 Porsche 912. The shell went back to bare metal for crash and rust repairs, and after that I epoxy primed it and block-sanded it for paint. Video of that here! https://youtu.be/wT37apmGdLY
Prepping bodywork is filthy and time-consuming, but I found the process extremely cathartic (to the point where I think I'd be quite happy to do it every day as a job). The end result really is worth all the effort.
Anyway, doing this cowl today took me right back to that state of mind. I began fiddling with the panel gaps, which were not good, and then things started to work out. They're not as beautiful David Howe's Harmon Rocket (Hi David), but they're significantly better than they were
and should make this aircraft a lot easier on the eye. Here's the end result...