Yes all that would work.
Standby - SPST right after the rectifier will be fine.
I'd use a 50K trim pot in series with a 33-39K resistor (or fine tune the value of the fixed resistor to give say 40-45mA max with your preferred brand of tubes.
The value of your 220K dropping resistor might need some tweaking to perfect bias pot sweep, maybe 150K, 180K etc (@3W)...depends on your final B+. Bigger value = more plate current.
An original 5F6A will show around 470vdc (+/-10v) on the power tube plates at reasonable plate current, with a GZ34. Add 5v or so for SS rectification, so maybe 465-485 might be ball park (345-0-345VAC to 360-0-360VAC B+ winding)? I wouldn't be heartbroken if B+ was another few volts adrift either side of this (a lot of factors affect final B+). RI schem shows 490vdc with SS rectification...in reality they can well exceed 500vdc.