Originals are generally in the 24-32" x around 1-1.5" thick x up to 8" wide - the one in the Last of the Mohicans movie was made deliberately oversize (about 33%), although there are some pictured by G Catlin approaching that size
Some examples:
two by me - both maple stocks.............
same one all gussied up western style........
another westernized one...........
some originals........
The one that inspired those above - it's 27" long - you can scale from there...
others...........
These descriptions referto those in the above image.......
John Baldwin has a book, "Indian Warclubs" (available from
www.crazycrow.com item # 4153-004-255) - not cheap but worth it