Elevated Heater & B+ Voltage

[Audiophile]

Hi Folks, Its been a while! I thought I had given up but Im back messing with valves for friends....
I was wondering if someone could look at my elevated heater circuit and just check Ive got it right, I dont even know if I need it, Ive read that this should be done for a CF and Im doing an SRPP but someone said I should elevate an SRPP so I thought I would ask here where the valve people live.

The other thing is my B+, the transformer is 180v, I was expecting about 254v DC but im measuring 279v un loaded. I dont really know what all the abbreviations mean so I dont even know if this is too much for the valve? I will attach a pic of its specs, looking at it through stupid eyes I see Ua 250v in characteristics so im thinking thats recommended? then I see Ua300v Max so im thinking Im ok but is there other factors/specs to consider?