351-W pnging badly

I have a rebuilt 351-w in my 55 sunliner that pings badly with the vacumn advance hooked up,its a 80s block and heads with a 80s factory cast iron intake and mid 70s duraspark distributor plus 2.79 gears and supposively a RV grind cam with a 302 firing order. I have tried setting the timing from 10 degress BTC to almost TDC and still the same even with the vacumn advance at full or ported vacumn,it runs great with the vacumn advance plugged and the timing set at 10 to 12 BTC. I have heard that a vacumn advance is needed for economy which I am trying to get as much as I can out of the boat without having to go to a AOD and different gears,its also running a tab rich but dont want to jet the carb untill I get the vacumn advance working correctly so is it time for a adjustable vacumn advance or a custom tweeked distributor. Jeff

Are you running an EGR valve?

No EGR valve is being used.