Power a preamp using power from valve heaters?

[mildew]

I want to put a "Fred Brigs' 'Face" into my valve junior before the signal hits v1.  Can i power it with voltage taken from the (DC) heater?

Can i get either 6.3 from pin 4/5,  or 12.6v from pin 9 from the ecc83?  Do i connect ground to any ground point or does it need a specific ground?

thanks in advance,