In the past, I've been lucky enough that the required spoke lengths for wheel builds have been close enough (< 2mm) that I could get by using all the same length spokes, which is a good savings for me since I can get a box of 100 at about half the price per spoke that I pay buying them individually from the LBS.

My newest build plan has spokes ranging from 164.3 on the drive side rear to 167.1 on the front. I'll be using double walled rims and brass nipples. Can I get by using the same length spokes? What would be the best spoke length to work with? I'm thinking of just ordering a box of 167s but since I have to order or travel about an hour to get any other spokes, I'm considering just picking up enough 165s for the drive side. Non-drive rear comes out to 165.9 on ProWheelbuilder's online calculator.

Here's another related question. I run my calculations through both ProWheelbuilder and FreeSpoke online calculators and almost always get slightly different lengths, sometimes up to 2mm different. ProWheelbuilder was recommended to me by a wheel building friend and so far it hasn't failed me, but just how big is the acceptable range of spoke lengths? As I always use double walled rims I tend to lean toward the long side as long as there is no risk of running out of threads before achieving the desired tension.