Agreed. No need to pull the head just to get it turning. Find the air inlet line and remove it. Get a hose barb that will screw into the port and some clear hose to fit it. Thread hose barb into the intake port. Slide clear hose onto the hose barb and clamp in place. The support the hose, say 12 inches or so, vertically. Use wire, a 2x4, whatever is handy. The point is to hold the hose up and let gravity do the work.
Fill hose with ATF. If it runs right in, fine. If not, fill the hose to the top and let it sit. It will work it's way in, you don't need to be there to watch it, and by using clear hose, it's easy to see if it's gone into the pump.
Done this a few times over the years on the farm... works great!