No, I'm afraid I don't know much more about the Crawford lines. So far I only have a very distant roundabout connection to the Crawfords in that book, and I haven't yet followed any lines forward.
I have another look through Beggs headstone photos I have. There is a David Beggs buried in Rashee, but it's earlier than yours. Maybe they're part of the same family though. This is what I can make out from the photo:
In
Memory of
DAVID BEGGS
who departed
this life the 2 ... Febr...
17[78?] ag.......lso MAI...
his wife who dep.......
life the ..0 of O... 179..
ag..7[5?] yr.... ..so their
son DAVID BEGGS
Me...an.. late of Ca....
....n who departed this
life the 11th .......
aged [8?]0 .....
Oh, another headstone from Rashee which may or may not be relevant:
ERECTED
BY
WILLIAM JOHN BAMFORD
To the Memory of his Father
JOHN BAMFORD, Lismanary
Died 29th May, 1861, Aged 67 Years
Also WILLIAM JOHN MILLAR
His Nephew died 29th October 1861
Aged 5 years
Also LEONORA JANE MILLAR
His Niece died [3?]rd April, 1862
Aged 8 years
Also his Mother LEANORA BAMFORD,
Died 31st May, 1872, Aged 74 years
Lismenary is on the north side of Ballynure, and isn't far from Ballyalbanagh, which also borders Ballyboley. There are a few Banfords of Ballyboley on the will calendars, including one who names a Hugh Beggs as executor.
[I wouldn't worry about the Bamford/Banford spelling differences. The above William John BaMford is called William John BaNford in his will, assuming it has been copied out faithfully.]