Power steering pump rebuild

I'm in the same stage of trying to remove the pulley. I have the same unit that you have 68 340. I installed the standard puller connecting to the front of the pulley using the hex shaped nut on the front soaking the shaft with PB Blaster for a couple of days. I tighten the puller a couple of times but no luck. I did not want to connect the puller to the back of the pulley thinking I would damage the pulley. I'll give it try and see what happens. Let u no