Polaroid instant camera film

Question

I have a One Step Land camera and I'm looking to buy film for it. The manual says that it uses SX-70 Land film. I'm only finding old SX-70 film(expired for 30 years!) Can the Polaroid 600 Instant film be used on this camera? The 600's description says that it works with CB-70/71/72 camera backs, but I don't know if the "70" on both refer to the same thing... The camera worked fine last time we used it and I promised my son that I would get him film for it for Christmas. I shouldn't have promised! Thanks for your help.