Neat jig Geof! I am sure that you went through this earlier thread
Hoods and Tonneau covers
The shape of the top is a tricky thing. I did not want a pronounced bend up in the middle
To do so I had to reduce the height of my roll bar (it was far too high anyway) and play around with the height of the bows a bit. I also wanted a bit of a slope at the back. The old sheet trick is a good way to test the options out!