Bob, yes, I still need the invoice (or Billing History card) to create an accurate window sticker.
Jim, I agree! We we all love to spend countless hours (and $$$) getting things "correct" on our cars, but honestly, there's only a small percentage of folks at cruise nights or car shows that notice correct master cylinders, lug nuts, etc. But 99% of ALL people that walk by your car, whether they're Firebird fanatics, or Pontiacs owners, or even casual muscle car fans, will stop and read your window sticker.
I started doing this business about a year ago. I've spent an enormous amount of time researching all the variances (text, alignments, etc) between assembly plants, and have worked at the Pontiac-Oakland Museum archives gathering information.
It was really the advent of the web that got me going on this project. As I saw more and more ORIGINAL window stickers posted on the web, I began to realize how wrong the PHS ones were. They use the wrong forms, and miss details like the separately typed partial VIN's that were in a different font, dealer codes, etc. that were on all ORIGINAL window stickers. The biggest problem I saw with PHS reproductions were the 1970-1971 years. PHS uses a generic 1972 form for all 1970-1971 models, which isn't even close to what the originals looked like (see my web page for details). I therefore had to create all my own proprietary forms from scratch, for all years, and all the different versions for the 1968-1969 Firebirds, 1970 Firebirds, and 1971-1972 Firebirds.
For 1st gen fans (my favorite), the 1968-1969 Firebird window sticker forms that PHS issues have the wrong border. Original 1968-1969 Firebird window stickers have a very narrow border, not the wide, lacy version that PHS uses. Also, the entire 1968-1969 form was a dark blue color, not the sky blue version that PHS uses.
I have a substantial list of dealer codes (far more than what's available on the web), but I do have some gaps here and there. Unfortunately, for those with 1968-earlier Billing History Cards, if I don't have the dealer name, I can't do the window sticker.