Well I have cracked the location of the shops in your photo and it's nowhere near 158 or 144 Whalley Road.
A free search of directories on Ancestry turns up the entry Bleasdale and Co, 233 Whalley Road Clayton. Don't know the type of business or the year, think you have to pay for that sort of information. The entry in question is towards the bottom of the first page of search results.
Bleasdale - U.K., City and County Directories, 1600s-1900s - Ancestry.co.uk
Anyway Streetview of that area takes me to the Volunteer pub, further out towards Harwood than we were looking. The address of the Volunteer is 229 Whalley Road, next door is a house, then a pair of houses with exactly the same upstairs window arrangement as in Mack's photo, and the bottom facade has been rebuilt, indicating that there were once shop frontages. 233 would have been Bleasdale's, the shop on the left.
So the photo was of the opposite side of the road to the tripe shop we have been looking for, and much further out of Clayton.
I was wrong about one thing - the shop on the right
is on a corner, of sorts - the next thing after it is the canal!