The last of the Miles 6-eyes that I was aware of are the 'Blackhawk' and 'Someday My Prince Will Come' LPs (which are also sometimes seen in later 2-eye pressings - I have the latter for example). All the later LPs were 2-eye in first pressings, to the best of my knowledge.
I have the 'Miles Smiles' in a pristine 2-eye and that one is a first pressing (at least I hope it is ).
Don't feel bad about buying both the originals and the Mosaic LPs. There's a strong case to be made for picking up both (not least for the alternates etc. on the Mosaics).
By the way, the 2-eye stereos usually also have 'Stereo 360 Degree Sound' plastered over the top of the labels.