Timing Question

Ok, so I have been unable to rid my engine of the dreaded pinging under load. I have changed springs and opened the slots to bring the timing in even later. All this to no avail, so I am now at the question. Is it possible with the overdrive 4 speed combined with the 2:76 geared rear axle, plus a 26 inch tire that I have such a high gearing that the engine is not got enough RPMs when all the timing comes in and the engine lugs, it can't use the available power quick enough and put it to the road to avoid pinging.... The car when you get it on the hi way will run 80 mph and the engine is only turning roughly 2100 rpms, and seems like there is no end to how much top end I have. Does anyone think that if I change the rear gear to a 3:23 or more this would help or cam change????????
this is what is in the car now it is roughly a 8 to 1 compression motor...

72 318 Block .30 over
79 318 Heads, not sure of the casting number think they are 72 cc chambers
1.88/1.60 valves
.23 head gasket
Purple cam 276/284 .444/.453" 112 degree
LD4B Edelbrock intake
650 Edelbrock carb
Windage tray
Double row timing chain
Mopar Electronic ignition with and orange ECU box

Thanks in advance.........