I've just purchased a full set of these Stainless Flanged Hex Head engine cover bolts.
Bolts are 8mm head with 11mm flange.
The kit that they list for the 750 doesn't have every external bolt listed so I made a list including the 3 for centre of the Alt Cover.
The flange Dia will have to be turned down slightly to fit in the recesses here and some others may need the length trimmed a whisker.
Mick