I don't think it will be that bad.
I just looked it up. I was wrong about the speed sensors. The four wheel sensors are direct to the ABS unit. ABS 5.3 sends the rear left wheel speed
to the DME (out of the ABS on pin 23).
What I'd check:
- Do you have a good vacuum connection from the engine intake to the brake booster?
- Check pins 17 and 18 on the ABS connector for +12V. They should be hot at all times.
- Check pin 15 for switched +12V.