question would be why would you? The old BFG's are at least 4-5 years old now, and would be hard as a rock.
If it is funding issue, I would talk to some racers in your area and see if they have an old set of Federals you could buy cheap. Most guys start the season with fresh rubber, so you might find som etires from the end of last season for prety cheap, that would be much better than the BFG's.