The cuts were made in the real dash middle part. It was re-installed between the top and bottom sections. There were two bolts which may have interfered with the gauges, so they were test fit on the bench. Sure enough, the speedometer and the oil pressure gauge mounting rings hit the bolt heads. The hex head bolts were removed and replaced with phillips round head bolts which provided enough clearance.
As this installation is intended to finalize all dash related connections, the defroster nozzles were installed and the hoses were cut to fit and installed. The right one was left long to allow adjustments. The left one is in a more congested area, so it was cut with a minimum of excess.
The dash was installed in the car. The clearance between the tachometer and the brake pedal support was checked. It is close, but a little trimming of the support and/or bending the electrical connection tabs on the light sockets will provide enough clearance.
A more critical interference was discovered between the headlight switch and the wiper motor. There is a possibility that cutting a new notch and rotating the switch may fix the problem. At worse, the switch section may need to be cut out and flipped around so the wiper switch is on the left and the headlight switch is on the right. Time will tell.