Hello,
I have one of Peter Abraham's belly plate repalcement panels and would definitly recomend contacting him, prompt service, fair price. As for the foam, A Foam Mart in Burbank (818) 848-3626 or Diamond Foam&Fabric in LA (323) 931-8148 will carry what you need. I used Ensolite foam to redo my vest and a friends, I think it's what came in the vest when I bought it. Ensolite comes in thicknesses from 1/4 inch to 1 inch. 3/4 inch is what came in my vest but I put in 1 inch in the belly pad, just works for me better, experiment. I recommend washing the nylon shells to remove all the old foam to help ease the insertion ( he said insertion!) of the new stuff. Hope this helps, I'll be glad to answer what I can. Take care, Nick