Re: John McBeath - Caithness
I found a birth record for John McBeath in Wick, Caithness -- born 10/19/1766 to James McBeath and Jean Sinclair.
There is another, born 1/11/1766 in Thurso, Caithness, to Andrew McBeath and Isob. Calder (Isob. might be Isobel perhaps; I pay the fee to see the original record).
Hope that helps!