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Thanks for the replies.
I did some searching, including the archives to get some ideas.
Tony Bingelis suggested how to find the center of the door.
Put it where the dipstick cover will be as it reaches the height of the cowl.
So mine ended up a little aft of the Vans current cowl and putting in oil will take a funnel. But it would have anyway probably.
I had already decided to try and use the cowl piece as the door before I saw AJ's post but, if I did it again I think I would go aluminum. Lighter.
I also used Vans dorky Mickey Mouse ears camlocs for three reasons. They were already paid for, they were lighter than the other brands, and required no tool to open. When I put them in I aligned the edges with a straight edge and drilled the rivet holes, so when closed they present an edge to the windstream. I can always Dremel off the wings for a screwdriver slot.
I had all the parts for the hinge except the spring so I fabricated the rest.
Not an award winner but I think i can be seen with it in public.
Dave A