To the OP: There's a lot that goes in to your equation: Film, typical use scenario, cost. If you shoot Tri-X or don't enlarge very big then it probably doesn't matter. If the f/2.8 is an AiS version (orange painted minimum f-stop) and you can swallow the price get it; it is better all around than the f/3.5. Otherwise the f/3.5 will be fine. Any signs of damage on either? Why the rush?
You pays your money and you takes your chances. Good luck.