master cylinder 4 discs, 73 dart front / mustang2 rear, manual

Guys,

I converted my rear brakes from drums to ford mustang 2 disc Brakes. In front I swapped to 73up discs ( had already 72 discs before).

As i was bleeding the brakes I felt the master cylinder might not carry enough fluid in his cylinder per stroke for the rear brakes since it is designed for drum brakes. Can this be? The pedal has a pressure Point almost down at the floor.
Do I need a master cylinder with more stroke? Using an adjustable pushrod.
Currently I have a diameter of 15/16 ( not sure, it is still the original power m/c from my 72 disc/drum car ) which brakes great and I don’t want to go much bigger in Piston diameter because I don’t have power brakes.

I found some master at Mancini MRE3360 (bore 1.031", stroke 1.55 ) & MRE3459 ( 1.125", no stroke given - too big???)

And the wilwood 260-4894 (bore 1.063" , stroke 1.35" )

I think less Diameter for good pressure and more strok for more fluid for the rear calipers?