its actually not as big of a difference as i thought. i took apart my own slab board 62 and realized the pickups are plain enamel. the 70's pickups are enamel as well. i dont know when and if heavy formvar was used. jimmy told me he tried a set of his pickups with plain enamel wire in an lm and he thought it was too bright. however, compared to a fender i dont think the lm's have the sparkle. he called it "glassy".
the winding on the 60's stuff could be all over the map though. the neck pickup in my 62 was reading at 5.3k and the bridge pickup was reading at 8.7k. i replaced the neck pickup with an antiquity 2 (plain enamel) that was wound to 8.1k and its a perfect match with the original bridge pickup. same airy quality, same amount of microphonics.
my 78 has pickups that are in the mid 7k range and i bought a set of 1980 pickups of off ebay for my 75 ri that read the same. i sent them to carey nordstrand to take notes for a future replication job and he said the coil looked small and he suspected 43 gauge plain enamel.
and im almost embarrassed that im this much of a pickup geek