6.1 Hemi 69 Barracuda Fastback Father Son Project

9’s up front realistically means 18’s or extensive fender work.

17x9 +0 won’t cut it. A 9” wheel up front realistically needs almost 6” of backspace to clear the fender (on a 73+ set up), a +0 is only 5” so even if you’ve got an extra 1/4” vs a standard 73+ set up that’s still no where near enough.

The problem is this- you still have the same clearance issue to the outer tie rod. Typically that’s an issue at around 5.6” of backspace with a 17”, for you that means it’s gonna be an issue at around 5.35”. So yeah, the 17x9 +0 for you is like an effective 5.25” of backspace compared to a 73+ brake set up, but you’d still realistically need close 5.75” to make the wheel actually fit in the fender, but that won’t clear the tie rod.

Like @mosleyme said, you have 17x8 +0’s on there now, your best bet is to measure the distance you’ve got from the outer tie rod end to your current wheel and take most of that distance and add it to the backspace of your current wheel to figure what you want on the next set.

And think about it this way, 17x9 +0’s will stick out an extra 1/2” compared to your current 17x8 +0’s. Centerline is the same, wheel lip moves out a 1/2” on both sides.
Doh! my bad, should have said, off the shelf one piece 17x9 5" BS would be for the rears...
I know those fit, same as what's on there now.
The Custom 2 piece 17x8 with custom BS, 5.25, 5.5, 5.75 etc. can be ordered and would be for the fronts.

I'll put the Year One 17x8s back on and measure wheel clearance to the OTR end.
Won't be exact because no front end alignment on the car, everything is just bolted together out of the box.
Eyeballed for everything and the torsion bars cranked up to keep the tires from hitting the fender lips.
It should give me some idea how much further back I can go though.

I'll measure clearance with the standard 11.75" rotors too. I'd be okay with going with the BS to fit the standard rotor and a spacer to use the same wheel with the 73 C-Body rotor...

Measure actual backspace of my 17x8s
Measure clearance to OTR end
17x8 BS + clearance to OTR = new wheel BS
Can always add minimal spacer if I end up too close to the otr after alignment.