The West Marystone (Merryston), I presume you are talking about is not in Coatbridge. It's was/is the area surrounding what is now Easterhouse Railway Station near to Baillieston beside the Monkland Canal.
The following is a link to a local Baillieston site on which there's quite a bit of history on that area.
http://groups.msn.com/Bailliestonnet/mc1.msnwCrosshill is also part of Baillieston. If you go to Multimap and key in NS682639, that will take you to 'today's' exact location. As cavvytri said, it was in the parish of Old Monkland which covered a pretty big area.
Also, if you go to:
http://www.old-maps.co.uk, and key in Baillieston, there is an 1864 map which shows Crosshill and Maryston. To find Maryston, just keep clicking up and it will eventually appear at the extreme right of the window. The titles Maryston, Marystown and Merryston have changed back and forwards over the years.
I have Lair Records and MI's for both churchyards in Baillieston, Crosshill and St. John's (Episcopalian) but the only McPhersons I can find are in St. John's and are a Duncan (died 12th May 1886 aged 76) & Mary Thom McPherson (nee Adam) his wife who died 25th October 1877 aged 55. According to the MI, Duncan was a Portioner from Whifflet in Coatbridge.
Great minds Lodger!! You beat me to it with the lnk to baillieston.net!