Let me give some more information -
I've breadboarded the circuit. It works fine driving a unipolar stepper motor.
S1 "Direction" will be removed. Direction will be an external input like Step.
The circuit will be part of an open source CNC router. Therefore Direction and Step will come from buffered and isolated external signals either a parallel port or micro controller.
The PCB will need 4 stand-offs so I can use a #4-40 screw [US, not metric] to mount it.
The Stepper will be under 2 amps MAX. More likely 1 amp.
The input/output connections will be .1" molex KK connectors. Total of 3 parts:
2 pin for power
2 pin for direction/step
6 pin for stepper
You have experience designing PCB professionally and advise me on best practices.
Design the board so I may optionally attach a heat sink onto the TIP31 transistors.
The full page for the circuit is:
https://www.aaroncake.net/circuits/stepper.asp
The guarantee I spoke of was more for the PCB to be technically correct and submittable to a PCB house.