I transcribed these records of McLea/McLay/etc from the abstracts of the taxt payments in 1710-1774 Apprentices of Great Britain. They contain a few records which may be of use, although this is only an index. There may be more information if you consult the original registers, although I am not aware if that is true, as I do not have access!

Anyway, have a look at these couple of entries from p. 3734 if you're interested! It contains records from throughout Great Britain, and it is said to contain about ~20% Scottish records. But only a couple of the McLea-type records are Scottish.

Here's the file: 1710-1774_UK_Apprentices.doc. Hope it's helpful!

Kyle=