Damn header leaks! wtd?
I have always used Mr. Gasket or Fel-pro with Permatex copper sealer. No problems with my 11.5 to 1 compression 383. Worst case scenario - you can have someone run a weld bead around each port and grind them flat around 1/16" to 1/8" higher than the flange. I know some guys who have done this on engines with crazy compression that were always blowing header gaskets. The beads have to be ground to the exact same height for it to work well.