70 dart side trim holes -bondo ?
what needs to be done to prep it for lead
Both sides will have to be cleaned, not just the front side of the hole but the back as well. Has to be clean, bare metal. Then you'll need to "tin" the area you want the lead to stick to, which is either done with an acid core solder or nowadays a "tinning butter" which can just be brushed on. After the metal has been tinned the lead can be applied. Once it cools it's solid and can be shaped with a body file. You'll want to take it down a little further than normal because you'll want a skim coat of regular filler over the top, you don't want to sand lead bodywork.
The hard part is getting the proper adhesion, especially to fill a hole, because some of the lead has to stick to the backside too.
Lead work takes practice, the old hot rod and custom builders were amazing at working lead. But it's kind of a dying art form, and it definitely takes some finesse. If you're not familiar with it, I'm not sure filling an entire cars worth of trim holes located right down the bodyline would be a good way to start.
