ECN Forum Forums General Topics of the Trade General Discussion Area calculating voltage drop for 2 RTUs

I have 2 roof top units, a 2.5 ton and a 3.5 ton. Together the RLA is 35.2A. The run is 120 feet. Using #6 THHN to a double disconnect, I come up with a 1.7% voltage drop at 240V. Am I figuring this right? If I use a 70A breaker will it hold if they both kick on at the same time?