Wiring harness and brake master cylinder reservoir mounting

 The fuse block gets mounted high and out of sight on the left kick panel, the front harness passes though a hole just behind the box ( be sure to seal it)  it is ran under the top of the wheel well where the front bonnet cable is mounted. For the rear section route it along the driver's side floor against the rocker and out the rear of the floor pan.

Not sure why you need a M/C mount bracket ?...The Beetle M/C gets mounted to the firewall in front of the pedal assembly, there are 2 sleeve that are about 3/4" that goes between the inner and outer firewall so that when you tighten the two M/C mounting bolts the firewall doesn't collapse.

This is what I used for the M/C reservoir.        

https://www2.cip1.com/ProductD...=VWC-113-611-301-DCC

It eliminates plumbing and moves the reservoir out of the trunk.  The downside is that you have to remove the front wheel to add fluid.  Not really a big deal and once your brakes are bled, you should not have to add fluid very often.  If so, you have other issues. 

I do the same as James describes above with the M/C reservoir. AND what the Doc does regrading the harness.

Front harness is up left kick-panel tucked away with the wires going through a small hole. Run it up along the tire well and down towards the drivers side headlights...

Rear harness runs along the driver side floor and out one of the holes in the pan (rubber o-ring to prevent wire chafing)... I then zip tie it to the sub-frame from the body and through the fire wall (for the engine wires...)

My Speedster build thread has a LOT of photos that might help...

That M/C reservoir is OEM from Volvo someone discovered it was a direct pop in fit .

Since you are a supporting member,  download the CMC assembly manual here.