If you've bought a Power Arc ignition and it's still sitting in the box, or you plan on buying one, here is the way that I figured out how to mount up the coil without having to modify or buy anything else. It may have already been covered somewhere else and I'm just unaware, but this is what worked for me.
If you'll look at the first picture, note that the stock coil brackets are "shorter stem" to the rear, and "longer stem" to the front.
When you take the coil packs out, make sure and save the screws (second picture) that mount the old coils to the brackets. You'll be reusing those.