318 carb issues

It just occurred to me that the pump nozzle size could be off... From what i've read my carb currently has a #31 nozzle, would it be best to try a bigger nozzle or smaller at first? Kind of torn because holley says smaller nozzles are best for heavy vehicles and/or vehicles with tall gears, and that bigger nozzles are best for vehicles with good power to weight. The truck isn't light compared to an A-body (its almost 5,000lbs), but it does have 3.55's and a 727. Stock 318 w/ dual plane 340 intake and 600 holley vacuum. Choke is no longer a factor as it has been tied off. TIA