I have some convex lenses salvaged from something I don't know identity of. They are good quality convex lenses, but useless for telescope making. Following is the detail:
 

L1- D-91.4mm, L-160mm, F1.75 (double convex)

L2- D-101.6mm, L130mm, F1.28 (concavo-convex)

L3- D-108mm, L170mm, F1.57 (concavo-convex)

L4- D-114mm, L260mm, F2.28 (plano-convex)

 Is it possible for me to grind these lenses to a usable F ratio?

Probably possible, but not likely to be practical.

Lens grinding and figuring is beyond most of the people who frequent these pages. Do some searching at the yahoo astronomy tech groups. One of the ATM groups might be a good place to start. 

Ikhanr

Even in the event you were able to grind them, then you would have to have them coated with anti-reflection compounds to make them usable.