Squarebird ball joints are not pressed in, they each have three rivets that must be drilled out then chiseled off. New ball joints should come with three cap screws with washers and nuts.
Spring compressors are not necessary and they won't fit between the spring and frame.
I like the idea of reconnecting the ball joint studs without the upper bumper. All my cars had engines so the lower joint studs went in without any problem. - Dave