Shorty headers should be better! And adjusting TTI headers to not hit torsion bars is not uncommon. In TTI's defense, they designed their headers for Mopars built to dimensions! However, we've found out some of our Mopars are half an inch (or more) out of specifications!! Thrust me, Shivvy and...
If you're going with the shorty headers, they only come in 1 5/8 tubes.
I personally have not used any small block TTI Shorty Headers, but the long tube headers sure fit nice. No issues with the oil filter or Mopar mini starters. Some aftermarket mini starters have weird electrical posts that...
Call Vintage Air. I'm pretty sure they sell a kit the will work with your factory AC dash and switch over to the more modern rotary compressor that uses a double v-belt pulley like original.
As long as both are the same splines. They came either 10 splines or 29 splines. At least the 741/742 8 3/4 rears did.
Also, the 489 case used a crush sleeve to set the pinion gear depth. If you crush that collar more, you'll mess up the gear mess. They sell a shim kit that you can replace the...
If you don't mind spending a little more money, Ever cost Rage Ultra is actually a little easier to sand and is more flexible than regular Bondo. Since the seem between the quarter and roof is pretty long, a more flexible filler might be better.
I have not used Huge's kit, but it will work. Actually I like the idea of using the 85 water pump housing. It will make the engine look more like an original instead of later model magnum. Stealth! 😁
It looks like a "6 of one, half dozen of another" at witch way you install the harness. Removing four wires from the connector isn't too difficult.
On a side note, I'm kinda envious neither one of my E-Bodies have cruise control. Even my 64 Imperial is sans cruise control. Sigh!
I believe you're on the right track with having to disconnect the plug and run the wires through and reinstall the plug. PITA, but the factory manual shows dashed lines between the wires and plug.
The package tray can actually be put in anytime before the rear seat back, but before the rear inner window trim might help position the trim. Hard headliner would have been easier before the windshield, but should slide in with the door and quarter windows down.
Unless I missed something, I thought it is a 74 Barracuda and it would have the ECS tank. The supply tube is 5/16" ID and the return line is 14" ID. Should work great with a Holley electric pump and the regulator he is looking at. 🙂
Gran Coupe Plymouth Barracuda and SE Dodge Challenger had very similar options. Cardboard headliner (coupes) with overhead console were similar.
On a side note, I find it interesting that Plymouth made the Gran Coupe it's own body style (BP23 or BP27) while for the Challenger it was an option...