Driveshaft Length

[NAPA 68]

What experience have some of you had with the maximum length for a 1 pc. driveshaft? As some of you may have seen, I am in the process of building a 59 Bel Air. I was curious what the parameters are for determining when a person should have a 2 pc. shaft. BTW, the car will require a 57" shaft center to center on the yokes.

Thanks,

Tim