I checked findagrave.com and billiongraves.com, but it doesn't appear on either site. That's not to say it's not in the churchyard, just that it's not listed on those sites yet.
You could try contacting Cheshire Family History Society who did the transcriptions. Sometimes Family History Societies produce CDs of work they have undertaken like MIs.
You could try contacting the church to ask them is there is a gravestone with an MI on - especially if you offer a donation to their church restoration fund!
You may have to visit the church yard, and armed with the information this transcription gives you, find the actual grave.
Or you could put a plea out on Rootschat for anybody who lives in Stockport to see if they can find it for you.
Wonderful as the internet is, not all family history research can be done via it.
