Stop in for a cup of coffee

WV64Signet said
What's interesting is that the old one was with the car having drums all the way around....

That is an unusual twist.
Functionally, if the bore diameter is the same as the drum, the stroke will be very close, and the only difference will be a residual valve for the drums.
The residual valve keeps the wheel cylinders from retracting too far as well keeping air out of the lines.
page 4 of 1967 Chrysler Dual Hydraulic Brake System from the Master Technicians Service Conference
page 5 of 1967 Chrysler Dual Hydraulic Brake System from the Master Technicians Service Conference

(to flip through the pages, manually type the page number into the URL. Someone goofed and loaded the pages to a usrl with the P in Page capitalized, but made the links to URLs wut ha small p in page. )