The fresh steelies look fantastic.
I gather that the Cooper Cobra tires are just about the same as he BFG Radial T/A and the MT Sportsman ST(?), they're all all-season tires...but they look sharp. My father has a brand new set on his '67 GTX (white letters in) and I think they look better than my BFGs. I hope they perform well for you!
Ha! That's great. You're raising that kid right! :D
It doesn't sound like you need a super stiff bar. I tend to agree with Johnny Dart on this one. The stock 340 bars would probably be just fine. He makes a good point about the bars being free of nicks. The vast majority of the stresses on these bars is carried on the very outer portion. A nick or a gouge could lead to a failure.
I will also just add that a lot of people have pointed out that even the "performance" bars from back then are much more softly sprung than we're used to from modern cars. If you're replacing them, maybe go a notch or two more stiff. I have 1.14" bars in mine. They're on the stiff side but even these are not uncomfortable (paired with Fox/Hotchkis shocks) IMO.