Have an opportunity to buy a 1974 Roadrunner but engine has issues and there is a hole in frame. $2500 fair price?

Look all in the cowl REAL good because that's where those cars are bad about rusting out. Open the doors and look forward of the hinges in the area forward of the firewall and under the cowl. Also look as good as you can into the cowl vents and look under the dash at the inside part of the cowl and around the corners where the cowl and the kick panel frame come together. If it's rusted out in any of the cowl area, I'd get it running and driving good and flip hell out of it.

I'll add- go ahead and remove those cowl vent screens and get your arm in as far as it will go.
Feel around the bottoms of the "stacks" that direct water around the actual vent openings.

If those are rusted out, that's a TON of work to make right and could involve removing lead and either replacing it or finding a replacement for it.

Note that repro replacement metal is not made.
E body panels are close but not exact- notably the vent stacks are square instead of round on a B body, and there are other differences.

Same deal for those panels that hold the door hinges.
E body is close.

MoparMarks on FBBO had some of these OEM panels available.