Joe and Dave are spot on, 750 Normale & Veloce cam covers are identical in their casting, the difference was in the machining, where the 6 plinths on the Veloce cover were milled off to make more room for the cam cover button under the Veloce air can - on a 750F it's a tight fit.
The reason for enlarging the hole from 12mm to 16mm was to make sure that the shoulder of the cam nut still has some 'meat' to pull / snug down on with the plinth milled off.
The cast boss for the Veloce wasn't drilled & tapped for the stud.
To convert a Normale cover to a Veloce cover is dead simple, mill the plinths down a bit (how much....difficult to say exactly but 2mm to 3mm is about right, drill the holes out to 16mm, extract the air filter stud, thinners wash the hole really well & screw in a length of threaded aluminium rod with locktite, then cut off & clean up the lump, remembering to drill a little dimple +- 6mm drill in the top of the aluminium peg to simulate the casting dimple... if you really need to........ it's under the air box & all but invisible.
The early Veloce cam nuts looked almost like the Normale ones missing the Bakelite, except that the base washer was round & not hexagonal, the later Veloce cam nuts were thin knurled black buttons with a 10mm hex in the middle, while the Normale ones were thick, knurled & had a 14mm hex in the middle. The reason for this change was that Alfa had been making 2 versions of the Veloce air can, one with a pressed dent underneath it for clearance on the 750F's (There's heaps of room in a Sprint), but this was getting complicated, so rather have one version of the air can & make the offending cam nut thinner. Same thing applied to the 101 Veloce / Normale covers.
Lastly The 750 cam covers are narrower than the 101 covers
Hey, no-one said Alfa was logical & they did have heaps of State 'Lira' to $$$pend.....
Ciao
Greig