"Someone" at some point changed the timing chain and gears. When they did the cam was advanced at least one tooth ( by the picture) . At least it wasn't retarded or you could have had piston to exhaust valve contact. The engine will certainly run better with a new chain but "aligning" the cam and crank properly will be MORE helpful.
'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