I used a 120 psi from my compressor. I reckon less psi will still do a fine job, I'm just "paranoid" as hell. IF a valve DOES drop, "off with your head"!
I used a breaker bar to rotate the engine around to do each cylinder. One time I didn't quite get it at EXACTLY TDC. When I applied the air pressure the piston immediatly went "down", which rotated the crank (of course) and the breaker bar and socket got "launched" in the process! That was ugly, if your going to use TDC you got to be SURE of where it is.
I kind of like that "rope trick", not sure I would use it, but I can see where it would work AND you wouldn't have to worry about loosing air pressure!