The book California Grizzly by Storer and Tevis, Jr. gives some reliable figures and some guesses about grizzly size.
Quoting:
The last captive, "Monarch", when killed after a long life in a public zoo where he was underexercised and probably overfed, weighed 1127 pounds. Adams' big captive, "Samson", was several times reported to weigh more than 1500 pounds. One report of 1856 states that a "mammoth grizzly", taken in what is now El Dorado County, afforded no less than 1100 pounds of meat (which yielded the hunter $1375). Of two killed in the hills near Matilija Canyon, Ventura County in September, 1882, it was stated: "The largest…would weigh about 1500 pounds; it was all two strong horses could do to drag it…"
More quoting:
Seton was of the opinion that no true grizzly ever weighed 1500 pounds or that any but the California grizzly reached 1000 pounds; he gave 600 pounds as the average weight for males, and 500 for females.
Exit quoting.
The book has lots of other feature measurements, claws, skulls, etc.
Another book that may be of interest is A Grizzly Introduction to the Santa Ana Mountains by Jim Sleeper.
Moderator: If I am breaking any rules by quoting from the book please feel free to delete this post.