I need advice on tuning a freshly rebuilt 350 in my 1970 LeMans.

With the vacuum advance disconnected:
- At 6 DBTDC (17" vacuum) has poor performance and little to no ping
- At required 9 DBTDC (17.5" Vacuum) has mediocre acceleration with a slight ping and still runs at near 200 degrees temp.
- At 10.5 DBTDC (18" vacuum), runs hotter (215 Temp) with more ping
- At 12 DBTDC (18.5" vacuum), runs even hotter with even more ping.

When the Vaccum advance is reconnected, the performance drops and the pinging is much greater.

I have checked for other vacuum leaks and found none. The Quadrajet was freshly rebuilt but originally tuned for a 400.

1969 XS Block 350 with the std 9779067 grind cam. Rebuilt Quadrajet from a Firebird 400 and an HEI ignition.

I have struggled wit this for weeks and am at the end of my rope. Please help.