Guys,

It idles and goes off idle to half throttle with no backfiring!!!!

The only change I made was to drill "breather" holes in the distributor cap and re-lash the valves. Looks like the valves were lashed too tight and when oil pressure built, they were opening the exhaust valves early.

TECHINSPECTOR1, looks like you nailed it.

I'm hopeful this is the fix. Thanks for all the help and suggestions.

Mike