Thanks Carl, Bruce and Brian. We've trained the local Wombats to work while we're all asleep !. But seriously, this windshield, boot cowl, coaming and firewall assembly had been bothering me for some time because I could see how it was all inter-related. So I did a lot of reading of the manual, staring at the parts and reading other builder threads. Once you understand how the whole thing goes together, you can pre-empt what the downstream effect will be when you fit stuff together and it's not quite right. My first priority was making sure the boot cowl would mate against the windshield given that other builders seemed to have gapping there. I didn't want that so that took some juggling.

Gary, I have a separate angle that is notched which you then position to form to the profile of the boot cowl. The manual advises you to not match drill the angle to the firewall until you have the boot cowl in place. This allows you to match the cowl profile really well. So maybe you could make up a separate angle, notched to match the profile and then match drill ?

Ross and Eddie. So the curved back corners are required !. Blimey, as Eddie said, nothing the manual about that .... so I guess I need the heat gun again ... I actually thought this was just a manufacturing process effect.