this case is not new. some peoples have the same 'stamping' issue on their guitar.
the most simple explanation is : ibanez, or the people who manufacture
ibanez guitars, in this case must be fujigen guys, they just made it simple, stamp the neck with rosewood, sharktooth, binding, any color, says...'750', then the assembly guy will do the rest. if the neck 'married' with H-S-H bodies with no pickguard, then it's become 770. if the neck 'married' with H-S-S bodies, then it become 760..and so on.
same thing with '550' '570' etc...
maybe they just don't have time to make the stamp for each individual model.