Figured I'd beat up on Red and post pix for you guys since I had mine handy and close by.
Looks like the all the other Power Blocs I've used but the pucks are different. New number on the side of them is 0130-3003. I don't know the older clutch puck number.
They only go in one direction, as they are slightly tapered - the narrow end goes into the clutch body.
I don't remember the exact numbers, but I want to say that each washer is worth about 400 - 450 rpm of engagement change. More washers = a quicker engagement (that is the clutch will engage at a lower RPM).
Most people start around the 12-13 washer load and then back out to 10-11 depending on what hookup/engagement they're looking for. I think 11 gave me a 4200 launch in my last setup.
This will depend on the spring too. Don't have specs off hand for them, though.
Tuning Tip
If you're running a Power Bloc and the engage speed's up above 3500 or so, you will have to pull the gray wire out of the CDI unit to disable the reverse rev limiter. You will find the gray wire on the smaller (two lead) of the two Molex connectors that go into the CDI unit.
You can clip it off at the Molex, or if you're really anal about things, you can use a very tiny pick to push the keeper pins in (from the plug in side), pull the wire out of the Molex connector and then put heat shrink around it to keep it from grounding out against anything.
Snip and tuck's much easier.