I used Ames for my 69 (I know it is differnt) and it was great. You just need to put in on thin and do several light coats. Also do the thing we all used to do way back before the internet- call them. I know it is terribly uncomfortable sometimes to chat with someone when you can punch the keyboard, but the people at Ames are actually knowledgeable and able to assist with a question such as that. They really are the Pontiac People.
1969 Firebird 350 Coupe, Rust free Texas body, formerly brown, now a TA clone with quality spoiler, latching hood and TA wheel; 1969 GTO Convertible Expresso Brown/Parchment(currently painted red). Both numbers matching. My first love was a Cameo White 67 326 Coupe, bought back in 1983, at the age of 17, for $1,200. Been hooked since on PONTIAC! Working on a 67 400 ragtop for customization-Gulf Turquoise/Parchment/400/4 spd! My winter project!