Booster and Master Cylinder Disc Conversion 1967 Barracuda

I've got a 1967 Plymouth Barracuda 273. Came factory drum all around. I've swapped the front to a Mopar A Body factory disc conversion using components from a 1973 Plymouth Duster. Swap went great, did the suspension rebuild right away, all fit great. Put an 8 3/4 rear with disc conversion also. So I'm looking at discs at all 4 corners. Currently ordering parts to finish the brakes (stainless brake lines, hoses, clips, rear hose tee, etc from Inline Tube). The last couple parts I need are the booster and master cylinder. I know the Cardone 54-76101 Mopar reman booster seem to fit nicely, but they're unavailable now. I've found the exact same booster from BrakeBest, same part number, and it's actually available at $123.99. Here's the rub, the website says it'll fit a 1973 Plymouth Duster, but says it won't fit a 1967 Plymouth Barracuda. Both are Mopar A Bodies, did the firewall change between 67 and 73? Just don't wanna buy the wrong booster and find it doesn't bolt up.