twwen2,
Good job on the flushing. I'm proud of you.
Normally, I would prescribe what works for me, but I don't want to put you through unnecessary risk. I use a power washer on all my rads, but I'm worried about you damaging your pA120.3. My TCs have not been damaged on low settings on the power washer (its gas engined power lol) and I use that setting to blast my car wheels clean of brake dust, especially after a hard romp on a rainy day.
The outdoor tap should be plenty powerful for you. No sense being an egotistical hero (aka moron) like me :p: