At 12V?? It's gonna distort!
Set the ratio of plate and screen resistors like the ratio of typical plate and screen currents. Fiddle the cathode resistor to set the plate roughly halfway up the power supply voltage.
Squinting too deep in the dark corner, I estimate 5702 at 12V perhaps like this:
If that aint happy, disconnect that stuff from G2, tie G2 to plate. It's maybe a better triode than pentode. You'll still get more distortion from a well-whacked guitar than you'll know what to do with.