Painting inside cab and firewall

[Scott2]

I am getting ready to paint the firewall and inside the cab on my 1951 3100. The truck was originally maroon but some dickhead apparently chemically stripped the truck so there are only little shreds of color here and there remaining. I picked a metallic burgundy PPG mixed as a single stage for the inside and firewall -- the rest of the truck will be cleaned of the worst rust and grunge and treated to a coat of Penetrol.

Questions: where do you break the paint, specifically around the hood mating line and door jambs (see pics)? I'm thinking about the paint being exposed through the gaps and would like to minimize that.

I'll back tape the edges to keep it a soft edge but I'm thinking I may want to set the paint edge back about 1/4" from the actual edge. Make sense? Any better way to do this?

I searched for pics but it seems like everyone takes pics of the engine bay or interior only. Also, I know I already primed to the edge but I can easily sand some of that off to pull the paint back further.

All thoughts and suggestions appreciated! Pics would be great too.

Thanks!