Auto body repair & detailing: rusty roof, ford custom, surface coat

Question
I have a 1964 Ford Custom . The roof on the passenger side has about a 1"x10" rusted out hole
right where the roof meets the channel
I'm a novice and was going to attempt to put in a patch panel , but can't find one available
Can this repair be done with fiberglass?If so what steps do I take?

Answer
The best way...is to make an "ALL AROUND" WELD patch first (either from the back, or make a depression and weld on the top side) to seal out moister from the back side, then you won't need to work with a moister resistant filler (such as fiberglass), you'll be able to use bondo.

The second way...is to make a depression, fill it with fiberglass (but no higher than the surface), coat with bondo, sand flush, coat with top-coat, prime, paint--you get the idea.