I've had 2 over the years and I am of different opinions. The first one I inherited from my uncle after it had been used and abused. It was alright to shoot but would jam occasionally no matter what I did to it. I do believe that the years of neglect took their toll and wore out the the slide enough that it would hang up. Now that being said I came across a VG condition one at an estate sale that still had the original boxes of Remington ammo with it. Very few rounds put through it. I have used it considerably since then 500/600 rnds worth of target and hunting with no problems what so ever. (several moose and deer to its credit) I have talked to the older local gunsmith and he said keep it clean and use as little oil as possible to keep it from fouling. I have since retired that rifle and primarily used 300wm but I kept the -06 as a backup just in case.
If you're looking at an older Rem 742 really look it over well,specifically the locking lugs on the bolt as well as where the bolt lugs lock into the receiver. Make sure the bolt cycles smoothly and locks up every time,if they will let you shoot it first that would be best for checking the rifle.