According to an article in the May 2016 issue of Aviation History Magazine, the twelve B-17's that flew from CA to HI on 7 Dec 1941 were:
Four B-17C's of the 19th Bomb Group, 38th Recon Sqdron
Two B-17E's of the 19th Bomb Group, 38th Recon Sqdron
Six B-17E's of the 7th Bomb Group, 88th Recon Sqdron
B-17C 40-2074 was destroyed on landing when Japanese fighters hit and ignited the flares carried in the fuselage. Another B-17C was damaged beyond repair on landing. The two remaining B-17C's did not proceed to combat areas with the B-17E's.