I've just bought an engine casing with similar numbers Li 150 722*** and inside it has 19 01 0001 and no recess for an oil thrower , sticky's book ( orange one ) gives conflicting advice as it states in the cranckcase identification chart that the 7 prefix is for Li 125 ser 2 and ser 3 150 specials but at the back of the book in the section about innocenti upgrades and anomalies it refers to Li 150 ser 1 engine no 7****** , so who knows ???
As you say probably just Innocenti using up old stock , I used to own a 1966 150 special that had a chrome ring frame but according to " records " that didn't ever exist , but it did
