I've looked at a lot of datasheets for the G range pumps, and the exploded diagrams show very clearly exactly the same head arrangement, even the rotor has the same number of "bumps" so I think it's a fair bet that it'll fit. I've got a new rotor so I can twiddle that down the stator and see if it all looks OK.
My only concern is that perhaps the stator (and rotor) are slightly different diameters for some reason. But why go to the effort of tooling for the manufacture of just slightly different parts? I can't imagine that the rotors are cheap to manufacture.
So, I've bought it. Worst case is sell it on again.
My ML works OK, it's just that it's had many hours used as a water pump before I got it, and it's pumped tens of thousands of liters of manky veg over the years that I've owned it. The poor thing is a bit overdue some TLC.