The hub casting is the same whether it's an ABS setup on not, as is the drive flange & bearing components the only bit that's different apparently is the stub axle, although why that should be is a bit daft. The ABS axle has the castlated detentes for the magnetic pickup to count, casting & machining two types would seem costly when the ABS one would do both jobs.
I'm not sure of how viable it would be to retro fit ABS but if you were to go that route you would already have the correct front axles on the car.
M