I am in the process of preparing the beast for painting. I am noticing the 50 year old putty between the panels and at the seams is cracking and even non-existent. There are gaps on the windshield frame that I can see through. The other big area is the rocker panel below/behind door. All I see there is air! Does anyone have a suggestion as to what I could fill it with? Preferably something that will last, that I can paint over, and is easy to work with. Silicone caulk is a no-go as I have found paint does not stick to. Thank you.