Looks like it is built pretty good, I see hurricane clips on the perlins. Can’t see how it is attached at the bottom.
I am assuming you are looking to do it as a diy project? I’ll just tell you What I would do if I was doing it at my house, you need to make sure it meets code in your area.
Remove the 1x6’s laying flat on top of the perlins. Get some 2x12’s the sane width as the 2x6 perlins. Cut the 2x12 to length and find center on the top. Snap lines from your top center to the bottom corners, making a big wide “A” and cut. Place directly on top of the existing 2x6 and predrill and fasten with graduating length screws, 4", 6", 8", 10", home depot sells long timbertek screws designed for treated lumber.
Once they are all on I would add a row of 2x12 blocking at the ridge from one 2x12 to the next to form a sold ridge. Then add some hurricane straps on the insides tieing the 2x12 to the 2x6.
If they are on 16" centers you can use 1/2" plywood on top, 24" will require 5/8" ,or might be different in your area, then install underlayment and your metal on top.
Just an idea of how I would do it if it was in my property and to meet code in my area.