If the new ball joints bolt-in, there's no press needed.As an alternative to renting the tool, HF sells an $80 press kit. I have used it a few times and it seems to be holding up. I haven't uses it on my ball joints yet but that's the plan.
I guess the forged lower arms have press-fit joints. My '88 has bolt-ins top and bottom. Knocking the rivets out is the worst part of the job; if the rivets are already gone (joints replaced before) the job is E-A-S-Y.