My apologies, looks like this was discussed maybe 40 pages ago and I entirely missed the memo.
These are just ideas...
Short version: if you're still showing knock at idle with your newly adjusted timing, try adding a little fuel and see if it reduces it or goes away. I'm not sure if it will completely go away with that size cam. Your 850 idle should be friendly enough.
Someone mentioned on page 11 that your O2 readings at idle may start to deceive you. This is true on EFI, the bigger the cam, the worse this can get. Much after 230° duration with a tight lobe separation (under computer control) can result in surging amongst other weird things requiring an OL idle. High MAP, overlap reversion, and fuel falling out of suspension (amplified on TBI than port injection).
Thanks for the sharing the information. I don't know about Edelbrock intake on these. I know the stock TBI intakes had issues with even fuel distribution, and was proved to me when I tried tuning my own stuff. At WOT, a 12.8 AFR would fall on its face no matter where I put the timing, and idle fueling would be all over the place, especially after warming up.
I read somewhere that even though your O2 might show great average readings, a couple cylinders may be more rich or more lean than the others...And the lean ones will knock first.
In my case - When I added fuel to mine, power came back and the knock went away. After that I could continue messing with timing again.