Here are some Hawken dimensions. Jim Bridger was over six feet tall and his rifle (I measured it at Helena, MT) has a barrel 33.25" ahead of the snail, 1.175 across the flats (ATF) there to 1.125 at the muzzle. Length of pull (LOP) is 13.5 inches. Weight 11 1/4 pounds.
Kit Carson was 5.2" and his rifle has a LOP of 13.25".
Liver Eating Johnson was 6'2", 260 pounds, and his rifle (measured by me at the Cody Firearms Museum) has a 31.75" barrel, 1.3 to 1.218 (heavy, and .54 caliber as I measured it- the muzzle is relieved, giving a false reading of about .56 caliber). LOP is 13.375". Page 375 of Jim Gordon's book "Great Gunmakers for the Early West, Volume III".
An S. Hawken I measured at Cheyenne has a 35.5" barrel, .54 caliber, 13.875" LOP. The Robidoux Hawken at Lincoln has a 32.125" .50 barrel, 1.125 to 1.090, and a LOP of 13.5".
An S. Hawken with pistol grip at Cody has a 32.56" barrel 1.145 to 1.155 (that's right) and a 13.5" LOP (page 391 of Jim Gordon's book). A capbox Hawken there (page 388 of Gordon) has a 31.81" barrel, 1 inch straight, LOP 13.625".
The W.S. Hawken at Cody has a 32.25" barrel 1.13 to 1.01, LOP 13.81". It is so different, not much like a Hawken, I didn't like it. The bore was so rusted I couldn't get a caliber reading on it. Page 401 of Gordon's book.
I also measured a J&S Hawken at Helena but can't find my notes. I posted about it in the Antique Rifle board here, probably about October, 2012.
Then there is the Parkman Hawken (Muzzle Blasts, August, 2010). .50 caliber, barrel 42.625", 1.125 to 1.00. Weight "some 15 pounds". LOP 13.125". When Parkman got back from the Rocky Mountains, he gave this rifle to his guide- maybe because it was too much rifle to shoot well. It had a walnut stock and a straight breech, not slant.
One important consideration in the trigger reach of these rifles is that they were used by mountain men who carried them every day, and they wore heavy buffalo coats for much of the winter. I made a .54 Leman with a 24" barrel and a 12.75" LOP, but found it too long for my winter coat and back pack strap for elk hunting. I'd like it a half inch shorter. I have a 32.5" sleeve length.