Need help, mustang guy helping a buddy with a chevelle.

[Hank70SS]

I don't know 67's very well but your list sounds good. also look at cowl near the windshield. Hard to see but firewall/cowl where it goes behind the inner fenders too. Water from the cowl drains through there and out the bottom of the fender in front of the door.

Also look at the frame where it curves out from the engine and goes under the firewall. If it's a big block car that area takes a lot of stress and can start to crack. Look along the inside edges of the curves.