Does your gas over there have lead in it? if not, besides the roller/flat tappet issues today are ones about exhaust seats on the earlier cyl heads that won't survive unleaded fuels. And with your piston issues---I'd have to suggest that you take a serious look at using new pistons( removing the amount of material you need to do will cause a severe balance issue ) and sell off your hi compression ones, also consider the usage of the Edel heads for the new type seats, plus tremendous weight saving.
also maybe with the new heads (open chamber?) your compression could be low enough not to have to deal with the piston domes ( closed chamber pistons will clear open chamber heads but not vice vs)