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TSE High B negativce?

I posted this while I was building My TSE with 300B tubes. I'm using an Edcor XPWR131-120 power transformer with 660 volt center tapped. I have an 8.2uf cap for C4. My B+ is at 365 to 370 volts depending on what my AC is doing. That what I was aiming for. But my B- is at -280 volts. The schematic says -150 volts. When I posted this I was told the that the B- on the schematic was for 45 tubes and the high B- was OK with 300B tubes?
In jdrouin's build thread, he says he changed R7 to 6.8K ohms to lower his B- to 150 volts with positive results.
Is this something that I should do?
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I also removed one hexfred and changed the value of R7. The two resistors are now: R6 (10k 25w) and R7 (6.8K 25W). I used 25w heatsinked chassis mount resistors to burn off all the extra heat. See here and pack to post #134 in that thread.

FWIW, other TSE 300B builders say a B- of -300V is fine. There may be other factors at play in my build, but I noticed a substantial improvement in sound by bringing the B- down to -150V.