Replacing the O2 sensors (car is 67 Mustang, engine is 91 5.0, no smog, stock computer, harness, etc, long tube headers). Not going to be doing any tuning immediately (donor car was tuned to match the TF HCI kit and stroker kit), but don't want to be replacing parts again if I want to tune later. Almost completely ignorant on tuning EFI; I've read on here enough to know that "wideband O2 sensors" or something to that effect is necessary for proper tuning. What do I need to buy now so that I have the capability to upgrade later, without buying replacement stuff? Thanks!