Hi Sirius,
Sorry, can't find them.
They're definately not in St. John's as I have a copy of all the records from as early as 1850.
As for the Old Parish Churchyard, I have a copy of MI's taken by a Mrs Jenny Gilmour in the 1960's (approx.) and I re-did them recently but no sign there either.
There are other Morrison's but I don't know if any of them would be related to yours. Let me know if you want a wee note of them and I'll send them on.
Anne