Glenbow Museum in Calgary has some interesting photos showing western Canada bows on their website
www.glenbow.org/collections/.
Image No. NA-1677-10 Sweetgrass, Manitoba Cree, 1872
NA-1406-124 First Nations of Eastern Canada, 1879 ( shows what appear to be d/r bows)
NA-843-31 Cree hunting equipment, western Canada, 1881
NA-1716-2 & Na-716-3 Joseph "Joe" Healy, Blood, in war dress, including bow, arrows and quiver, 1886
Na-1297-6 Mark Poucette, Stony, 1900
NA-1773-27 Blackfoot bows with bows and arrows, 1885
Not all Cree, but likely similar.
These photos are also available from Glenbow on high def DVD.
I numerous times saw an actual bow and arrow (Blackfeet?) on permanent display in the museum with other artifacts, including a scalp taken in fighting. If you visit there, it would be easy to estimate the dimensions. Their archival staff are also very helpful and would probably provide you with info on Cree weapons.