Get #1 cylinder at tdc, if... if #1 is at tdc the marker on your timing cover should be sitting at 0 degrees on the balancer. The hole gorilla tap idea is not good idea IMO. When you check the timing have someone run the engine up to 3000 rpm and you should not be over 30 degrees btdc. Also pulling the distributor cap off while its sitting at TDC the rotor should be pointing right at the #1 cylinder. If it is off that means your a cog or 2 off on the distributor and your timing marks will be inaccurate. Secondly low octane fuel in a higher compression engine will cause ping also.

HAHA sorry didn't see your ordeal about the cracked flex plate