My '70 Roadrunner underside is bare metal, now what?

[Big Lebowski]

What did a factory non-undercoated '70 B body look like? Is it over restoring it to paint the entire underside? I'm hearing that overspray only covered the first 16" of the sides, so what did the tunnel area look like?
A bronze '70 Hemi Roadrunner in a recent muscle car mag. showed a silver base coat in the tunnel area, but my painter buddy said the silver base coat was only for the bronze color?
What would you do? Which Primer, or no primer, just seal it and B5 the entire bottom?
Thanks for the help. Dude

[purple70rt]

surface rust after a week

[tan top]

 this might be of some  help 69 daytona B5

[Nacho-RT74]

I have a pair of NOS lower grills to yourt RR... juts if you are interested in one

[Big Lebowski]

  Thanks for the help. I'm hearing over at Moparts that Los Angeles Road runners came with a charcoal black underside with very little paint overspray. And my buddy Dallas who actually worked for Mopar in the 70's said that Chrysler was so cheap that the B5 blue overspray was barely there.
   Here's the strange part, this car was undercoated from the factory, but my buddy who owns it wants the over restored look with the entire underside painted B5 blue. So is that over restoring it? He doesn't want the overcoating put back on because Mopar purists think you're trying to hide something like rust or whatever. What do you think?