The difference is negligible. Keep in mind that the V35 came with KT90 tubes. So if you use 6550 tubes the output will be slightly less. Also the bias pot range is tight on both the Classic and V series. You might have to change a couple of resistors if you want to run 6550 tubes in a V series amp.
The V series is basally a balanced version of the Classic amps. Some of the very last Classic amps were also balanced. I have owned both the Classic 60 and V70. These are two of my very favorite ARC amps. I wish I had never sold my V70. Just wonderful sounding amps.