On the schematic the voltage is shown as 170-230v, which most tubes will achieve. But actually, the maximum workable range is 125 to 325v. It won't hurt anything to leave it as is.
But hopefully, the high voltage at T7 just means the driver tube has not been fully broken in - technically the cathode is not fully formed. Typically this means to operate the amp for 50-100 hours and check the voltages again. This is what I would do if it were my amp.
If you are in a hurry, a test of this theory would be to swap the 12AT7's from side to side and see if the high voltage follows the tube. That would at least help determine that the wiring around the tubes is good. It's not a 100% unequivocal test, since the 12AT7 has two triodes and only one is used - and they are different from side to side.