Manual or power brakes and a question on both

[Volksnut]

Okay '63 D100, added disc brakes to the front, factory drum rear. For master cylinders I have in my possession the recommended '72 master from Scarebird, but I also have the power brake kit from China. But....I see issues with both.

The manual master doesn't have a dust boot, that's no biggie I could tap and install one, and the pushrod hole is of small diameter and doesn't protrude deep, almost like it's a power master...will that matter to run it this way.

On the power master I read you have to modify the firewall for the bracket???? But on mocking it up it appears the arm kits before the bracket, no bending of the firewall lip will cure this. Do you cut off that stud to make it shorter, it's screwed in all the way in picture.

Any debates on running power over manual. Id hate to run the manual only to find I'd would be happier with power, and or is it worth modifying the firewall to get it to fit or am I just over looking something simple.