Well, for what it's worth, I have been a PPG Paint rep for over 20 years, I collect and restore as well, so if you want to use PPG products, here's some info. Your best bet on the bare metal is DP Epoxy primer. it has excellent adhesion, and corrosion protection, and you can bondo on top of it after it cures. This will keep any moisture from getting to your bare metal during the whole restoration process, and the bondo will stick better to this product than it will to the bare metal. DEFINATELY DO NOT USE rattle can products on the bare metal first, if your foundation is weak, the rest of the money you spend on products will be wasted....
As for primer surfacer, K-36 or K-38 high build is a solid choice, there are many newer products to choose from, but these are old stand bys that work well, and won't break the bank. If you're going base/clear, Deltron basecoat (DBC) is very reliable and affordable. As for Cloearcoats, there are many options, depending on where the car will be painted, ideally, rent a spray booth that has baking capabilities, you'll be thanking yourself when the job's done. The most popular Clearcoat for a restoration in my area is DCU 2021. This stuff is easy to spray, has excellent gloss and durability, and isn't terribly hard to wetsand and buff. If the car will be a solid color, and you don't want a clearcoat, use Concept Acrylic Uretahne (DCC). This stuff is a bit tougher to deal with, but the results are awesome gloss and excellent durability. It does not buff that easy, so here agian, rent a good spray booth, or pay a professional to shoot it. It will be money well spent.. By the way, expect to spend at least a grand on paint and materials. There are other products out there that are much cheaper, but remember, you get what you pay for.... Hope this helps, and good luck, Mike