went to the santa fe trails rendezvous this morning and found the book " Hawken Rifles, The mountain mans choice. John d. baird.
This book has amazing stuff inside it that covers everything from the beginning all the way to the end when they were converting the hawken over to the Spencer style cartridge rifle. They have pictures of the Hawken/Spencer conversion which looks pretty cool.
They also have info on the breech loading hawken ( 56-46 bottlenecked rimfire cartridge)
This book covers everything! even cheek piece info