[ARC5] BC-454-B tube question

[kg4kgl at gmail.com]

GM all,

 I have a question regarding the 12sk7 and 12sr7 tubes used in a BC-454-B receiver. The tube specs show max voltage for heater with respect to cathode as 90v. 

How was this dealt with in the original installations?

I built a SET amp that used 6sl7 driver tubes and a voltage divider (~83v) was created and fed to the center tap of the 6.3vac filament winding. Was any such thing done for these receivers? Should something similar be done if you are powering these from a B+ supply?

Thank you,

Robert S Jenkins
KG4KGL