Looking for advice before I start my first resto

Outstanding! a convertible!. I would worry about top side paint last. Maybe a good rub out or detail, but thats all. That is coming from a 30+ year paint and body guy. Bottom is important, but there are real deceptions out there - POR-15 is one of them. We conducted 60 cycle cyclic corrosion testing to ASTM standards with 7 of the paint over rust products. only one provided any "pass" results and POR-15 failed first. PM for more info on that.
I have owned a 67 fastback since 1986. These guys are right, parts are often "unobtaniom" for these cars now. hard to beat the looks - I love the styling. If you are going to put any amount of real power through it, plan on a set of welded in sub frame connectors.
NICE CAR