358V is a bit high I think and it is close to the maximum ratings for the 6F6 tubes…have the 6F6 tubes been tested and if so are they weak?
Also a good idea to measure all of the dogbone type resistors in that set since they tend to drift up in value over time and can upset bias voltages etc. I am currently working on a 37-650 as well ( just started ).
Important note here is to also check the candohm resistor ( item number 58 ) and I would recommend replacing it with discrete power resistors since these also drift in value and do eventually fail.
The basic rule is that if the bias voltages are not correct then the set will never work properly no matter what you do.