Crown left to right is a bit shallower. Thought I would do the fill in pieces. I decided to add a piece inner tube to the top wheel so it would work more as a roller and only bend in one direction. If both the upper and lower are metal, it compresses the metal as it passes through creating a compound curve rather than just bending it in one direction over the lower anvil with the rubber in place.
With the back pretty straight, it worked out nicely just using the upper wheel with the rubber for the whole thing. The 6mm-1/4" packers are there because the roof frame actually is not flat and is that much higher in the middle. So this makes sure all the shaping will suit the frame profile. The front is more tricky as will need a compound curve right at the front. I first washed over the whole piece with the rubber upper and my shallowest lower anvil and can see the first part is already the right curve.
I used the next anvil wheel with some more radius and only ran over the bottom 2/3rds. More contact has been made. Getting close to matching the bottom radius too on that second anvil. So will switch to the third anvil and concentrate at the top of the lower 1/3rd.
So only rolling with the rubber upper in the one direction for the whole thing, the curve is right in this direction. But if you look along the very front edge you can see it needs more curve to match the panels each side of it.
I made a profile gauge to what flowed along the front of the roof panel. Can see how the middle needs to come forward. What I did is remove the rubber and using the first lower anvil again, just washed over the first third front to rear, the opposite direction to before. That curved the front nicely to match the profile.