I have been all over this engine with a can of starting fluid, checked every vacuum port, there is no vacuum leak.
good
This engine is NOT running lean with this set up. I don't have to stick a sniffer on an exhaust pipe to know how it is running. The plugs are black, a rich solid black, not white and the exhaust reeks of and spews out raw gasoline. The engine runs out just fine, and I can't get it to spark knock, and that's not for a lack of trying.
ive never gotten spark knock on a slant... with anywhere from 7-8:1 comp its pretty hard...
as for the fuel issue why not get the carb jetted correctly not matter if its a related issue or not? just because its not a fuel issue dosn't mean the fuel wont cause an issue...
also have you checked the vacuum advance diaphragm with a tester? could be causing a vac leak...