Worked on header today.  Exhaust had leaks and backfired excessively on deceleration.  welded up all visible leaks in header.  Backfiring is better, but not completely gone.  Not wure if this is a tune thing or not.  Carbs have no filters on them, will order and install filter socks and see if this helps.  Ordered P. Bradens book on Weber carbs, I guess I better learn how to tune carbs.