I have no basis, but I can't help but think that this is a case of someone found a 16valve racing boat motor and jammed it into the closest thing to a GTA they had at the time... See also the Angelini 16valver (cooling layout suggests it's a single seater race car head. F2?) that's been put into a steel bodied GT more recently in the US.
A 64 GT is certainly a couple of years older than the lucas flat slide injection AFAIK
1966 Giulia Sprint GT Veloce - pretty much finished!
Bunch of bikes too.