Yes - I am hunting for a hard copy of that 1981 catalog! As soon as I find one, I'll take some detailed photos to post.
I agree - the 1981 catalog is the initial appearance of what seem to be the first true "in-house" ESP built LPs. Long tenon is the easiest indicator.
The strange thing, for me, is the two different headstock designs in the April 1978 catalog. I am assuming both styles were Kasuga made back then as well, but just seems strange that there would have been two very different designs like that, made by the same maker, doesn't it?
I also think that, from mid-1980 forward, at least for a couple of years (1981, 1982) there might have been two different levels of Navigator production: the top LPS models were made in-house at ESP, and the lower LPS models were likely still outsourced to Kasuga for production.