There's a guy in California who (i believe) has the last very few Davis cue blanks.
His name is martin Bick: http://www.superiorcues.com/JDBlanks1.html
He might have something ready made or ask if he is available to build for you. (this is your best source)
Martin has a list of cuemakers he recommends. Joe Lolley from Bama cues has a very nice Esoteric Davis full splice on Open Billiards on Facebook. Jose Gutierrez has a Prince Davis full splice.