Wanted 6-1/4" Midland Brake Booster 69 A-Body

dpalsmeier said
The 6" suggestion came from my Friday phone call with Booster Steve.
Also, 6-1/4" Midland (small photo) appears on the website for Harmon Classic Brakes.

Got you, sounds like you are going with a non-factory/MOPAR set-up, best of luck.