Scott, I would love to see a picture of your installed harness bar? And did you install it yourself? Only supplier I can see today is Mulfab, although I am sure there used to be others?
I am trying to install 3 point seatbelts in my DHC. But the inner wings are extremely narrow because of additional boards that screen the hood frame. Look like the answer could be a harness bar on the arches, but more or less abutted to the bulkhead.
Cheers, Colin