I used a master power brake kit.
the one I used had a generic booster and gm master cylinder.
they have since started making one that uses the new mopar master cylinder as well.
The booster bolts onto a bracket that fits onto the firewall with some adjustment, and then bolts directly onto the old pedal. Though mine has 2 holes in it, and it asks to be put in the upper hole as I recall.
So I didn't have to find anything to make it work.
I did have to add a bracket that I made to make the pedal hit the brake light switch though, after adding the kit.
the pedal did not return high enough after that to shut off the brake lights without it, and I could not adjust the switch far enough down to touch.
65 b body.