I have been looking for a 70 Roadrunner for some time. I am very close to going to see this car in person and pulling the trigger. I know a lot can be learned from looking at the trunk area of a car but I’m just not that educated in this area. Anybody see anything troubling here or does all look 1970 legit? Thank you in advance.

Seam sealer & general floor appearance (spot welds, metal) look about right, though it appears the plugs are missing.
Looks like overspray on the side marker retainers; nothing should be oversprayed in the trunk.
I can't clearly see if the fuel tank vent line is there, should be natural finish.
Inner faces of quarters should have a heavy coating of sound deadener, masked at side marker areas.
I don't have my '68 here to confirm, but IIRC there should be a few more (plugged) big drain holes closer to the rear body panel.
Look underneath, at the quarter drops, for a drain hole in each one, those also get vinyl plugs with a drain contour.
Rear wiring harness should have a woven fabric sheath over the length of the wire bundle. Those did decompose over time.
In one photo it looks like an added ground wire. Could be a problem.
Get in the trunk, look (or feel) below rear window & up the C-pillars for rust, welds low on the pillars, "bondo worms".
If you see a seam running along a quarter from tail lamps forward (where panel goes from top to side), quarter has been partially replaced.
Also look at the underside of the trunk lid especially at the rear, and give it a shake up/down listening for rust particles.
See if there's at least a spare wheel, if not a wheel & tire. There's also some hold-down stuff for that.

Thank you. Wow! That’s pretty amazing what you can tell about a car just from the trunk area. I will definitely be checking all of the things you mentioned. The car has been painted before but in the original color. I did notice the plugs were missing but figured those have got to be repopped by somebody. What kind of problem could the ground wire you mentioned be masking?

Plugs are available, no worries. Make sure the quarter drops have the D-shaped drain holes.
Adding that ground wire could indicate a lamp wiring issue, or something added; the floor isn't the most artistic place, a tail lamp stud would be nicer.
There are a million places to look, not sure what you know...
Wrinkles, buckles, welds at aprons, radiator support, frame rails.
Odd panel and molding gaps, wiring issues (melted, patched).
Numbers (rad support, engine, trans).
Fender tag info and if it's really an RM VIN0 car.
All the correct trim level stuff, base or Decor.
Hopefully the car has a long-term and known history.

There's a wealth of knowledge here; if you post photos and info, folks can chip in with what they see.
Good luck !

Car has fender tag and full build sheet. Has a Govier report from 2007 if that’s worth anything. VIN tag matches rad support and build sheet. VIN tag still has what look to be original rosette style rivets. Motor is non #’s but trans and Dana are said to be original. Original V code, 4 speed, Dana car. I think I know probably just enough to avoid buying a turd thankfully. Thanks for all the advice. I have taken notes on all of it, believe me.