1968 Plymouth Valiant First Gen HEMI
Man I like looking at the pictures of your engine compartments.
“…..You could try and fit power brakes on it …..”
That’s an option I’ve in the back of my head for a while if I can’t get the manual brakes to work out. I did a similar conversion on a customers car several years ago. He managed to find an aftermarket dual diaphragm unit that as I recall was a bit smaller in diameter than yours. I wish I could remember the company he got it from, but he passed several years ago and the cars in his collection got scattered to the 4 winds.