I don't know if I would subject an old rad to 20 psi pressure. I understand the process but I would assume that is an old rad in there.
When I remove the head from mine, I construct a support area on one of the front fenders using a soft towel, some bubble wrap and a piece of plywood. I then stand inside under the hood with my feet on the frame. I pick the head up and place it on the fender. I am 5' 11" and it works for me.
