Bill , I think this is a case of semantics. In this scenario high performance refers to "higher performance" or ported heads , not "289 high performance". Just as Huskinhano said there is NO difference in the size of the port openings or valve sizes between a "low performance head" anf the K code heads. ALL production intake gaskets for the 289's had openings for the heat riser. "Aftermarket" racing intake gaskets (at first) had thin metal plates that were used to block off the heat riser. Modern performance intake gaskets are simply blank ( no hole) in that area. Performance gaskets are not needed on non ported heads , there is no advantage at all.
'66 GT350H-3 time cover car - Car Craft July'77,Modified Mustangs and Fords Feb2011 ( w/article), Mustang Monthly June 2014. Bracket raced by me for the last 44 years. Yes it is a real one.
'68.5 R code GT fastback
'67 Ranchero 408W -427 glass hood
'78 F350 "Oleynik" car hauler
Ford Experimental parts collector