I have both brookvile and Howell's. Howell's roof insert didn't fit. It's now a front floor pan. I think brookville has the best quality.
Brookville seems to have the best fitment, but you'll pay for it. Howell's is cheap but most of the panels are only close and need tweaking. Sac Vintage Ford falls somewhere in the middle. Good luck!
Replaced the entire bottom of my sedan plus the roof piece over the door for $385 through Mike's-A-Fordable.
This is the cheapest method Cheap aftermarket panels are never any fun you will wish you just spent a little extra to get the panels that fit well and made your life easier, I once used an el' cheapo lower fender panel on a chevelle and I wound up cutting it all up and refabricating a lot of it to make it work and it still wasn't as nice as the year one panel I had for the other side.
I have quite a few of the Brookville panels lying around. Let me know what you need and if I have some or all of it I will make you a good deal on ti.