Heads up to those that install a 2 bolt aluminum master cylinder.

Go to a parts store and buy a master cyl for a 1979 Dodge Ram manual brakes. I could put someone through the windshield at 100mph. If installing it in an a-body with and adapter use a E-body or B-body brake push rod . This gives the extra length to make up for the adapter.

View attachment 1716014192
This is the part number for that unit. It shows the different port thread sizes. The rear port on mine does have the smaller threads so it does have the traditional arrangement.

RAYBESTOS MC39178 Specifications
Number of Ports2
Primary Port Thread A1/2"-20
Secondary Port Thread A9/16"-20

I'm still curious as to why I'm getting fluid to the rear brakes first.