Ryan, like you found in an old post of mine,
Mine calls for ATF too. I dont think there was such a thing as "Power steering fluid" in the 70's. I used ATF for ages. I switched to PS fluid for 1 reason: The ATF was not as viscous as PS fluid in the really cold temps and it would groan more, and it would be tougher to turn.
I bled mine in a similar fashion to what Tom Drew did. I pulled my old pump off and drained as much old PS (ATF) fluid I could by turning the wheel from lock to lock. Then I attached the new pump and pressure hose & blocked off the return on the pump and put my return hose into a gallon jug. Put in new ATF, bled as Tom Drew suggests - except I didn't have my wheels off the ground, but I didn't see any negative impact on that myself.