Hey T-Type, the 61 -64 frames are all the same also I hear the canadian pontiac frames are too. but the convert frame has 4 extra body mounts as well as extra plating on the X section to stiffen them up for the converts. you can easily reinforce a hardtop frame and add extra mounts if needed.
What are you working on I see you are out my way. Have you had any leads on frames locally? I am looking to replace mine in my conv as it was reinforced for hydros but plans changed as I aged and it never happened so to lighten it i want to swap it out for a stock frame with a few mods, hehe.
Would be good to hook up when the weather is nice enough for cruisin too!!