Sorry for the delay in replying - only just found your latest post. I'm glad you found the memorial at Undercliffe, but I don't know much about Kirkgate Chapel (which was Wesleyan).
I understand the registers are held by West Yorkshire Archives (Bradford branch), but I can't find Samuel in the index or images of these at Ancestry. Maybe the burial register hasn't been filmed?
The memorials were transcribed in 1928 by Arthur Blackburn, a local eccentric whose copious transcriptions are now in Bradford Local Studies Library. I think they would do a lookup for a nominal sum, if not free.
However, I've no idea whether the chapel is still standing, and even if it is, whether its graveyard might have been built on. Looking at the Alan Godfrey large scale map of 1906, I can't see any reference to a chapel actually on Kirkgate, although there's a Methodist Chapel marked on Baldwin Lane, which was like a continuation of James Street running from Godwin Street to Kirkgate. If this was the one, then it looks to me as though it's now underneath the modern Kirkgate shopping centre. Possibly someone in the library (or another RootsChatter) would know more.
Anyway, I hope this helps.
Arthur