master cylinder for 68 dart front disc

I did a search to see what master cylinder I would need for my 68 dart.
But I'm getting conflicting answers.

My 68 Dart GT originally had Drums all the way around. It's manual brake, no power.

I did a 4 piston KH swap a long time ago for the front and I dont remember why I didn't change the Master Cylinder.

Right now the car doesn't stop very hard and the pedal is really stiff.

Should I just tell my local parts store I need a master cylinder for a 1972 Dodge Dart with front disc/ rear drum and
no power ?

Does anyone have any part number for the correct master cylinder for this combination?

Someone recommended Raybestos MC36412 and also Raybestos MC36406.

Thank You in Advance.