Okay, update...
Back together and on the run stand...Cranked it up tonight and no knocking. Compression check was good. 125 to 130 psi on all six. Had one cylinder not firing...new plug wire and it came to life. Running really rich. Closed down the idle circuit and it cleaned up. Still not happy with the mixture (Carter YF) but a new carb is next. It's sitting on the shelf and I'll get it on in a day or do. It's a Holley Webber and I have to make an adapter to clear the valve cover.
Never did find a reason for the knocking on the first run. But I am very glad it didn't reappear this time. A few tweaks, a few shiny pieces need to be made and back into the truck it goes.
Needless to say, I'm a happy camper and I'll sleep a lot better tonight.
Paul
