Disc brake help

[atm70chevy]

I know this topic has been covered 1000 times but I still have some questions. I am new to this so any help would be greatly appreciated. I have a 1970 Chevy Stepside that someone has already swapped over to front disc brakes. I have completey rebuild the front suspension with parts for a 1970 Chevy. I found out the hard way that the lower ball joints will not work with a disc brake spindle. I have read that the lower ball joints will have to changed to 71-72. Do I have to change the upper ball joints as well as the tie rods? I have no idea what year model the spindles came from.... Any wisdom anyone can offer will really help me out.