What are your expectations? Realistically they will last forever. But if you are rebuilding everything anyway AND you are thinking about a little better handling now would be the time to go a little bigger. Or poly bushings (I personally have only on one end and rubber on the other so it get the best of both).
I know a little bit of that and gas shocks and a little quicker steering box and my Gran Sport made a BIG transformation when it comes to handling, that baby sticks pretty good.