First time having manual brakes, are mine bad?

Road Grabber said
I would be curious to know if the newer cars with factory four wheel disc brakes today have MCs with the same size reservoirs front and back?

Maybe If you try to compare these conversion systems with existing factory four wheel disc setup components it may help.
What proportion valves, metering blocks, master cylinder configurations do factory 4 disc systems have? Then you are comparing apples to apples. I would even consider mating components from other systems into your system that are known to work. At this point you have a custom brake system so as long as it bolts together who cares if you have to bend or fit your own brake lines to work with components known to work.

Fluid dynamics is fluid dynamics. You just need the right expert to lay it out and it will most likely be something very simple. One thing is for sure. Many others will benefit from the solution. Don’t give up.

Oh boy.

First, the OP is still running a disk/drum set up, so I don’t know why you’re talking about a disk/disk set up.

Second, reservoir size doesn’t change the pedal effort or the braking capabilities at all- unless the reservoir is too small and the ports suck air when the pedal is on the floor.

Third, I’m literally running the same master cylinder the OP now has. The reservoir size is not a problem. I have run the same size calipers and wheel cylinders. And I have run that same master cylinder with a disk/drum set up and disk/disk.

The OP does not have a mismatched parts problem, all of those parts work fine together if they’re functioning properly.