Engine pinging? what to do??

I have a 416 stroker which is supposed to have 11.6 comp. I can not keep the thing from pinging. It never did it with the auto and 4000 stall. Now that I have the 4 speed it wants to ping right when I lay into it. I recurved the MSD dist way back and even have a retard knob in the car so I can dial it WAYYY back and nothing helps. I run 5 to 7 gallons of 110 with 5 to 7 gallons of 92 mix. That should do it with my compression.

Other than trying straight race gas what can my problem be?

To much compression for my mildly ported E heads?

Cam is 262@50 and 613 lift, I'm running a Air gap dual plane?

Will better flowing heads make any difference?

I have plenty of fuel feeding the motor.

I run the same plug Scotty runs NGK R5671-8

I need some idea's, if I have to run straight race fuel in this thing then I might as well get some Indy D1's and make the power straight race fuel requires.

What do you guy's think?