Good Morning Richard,
	An interesting question.  Of all the literature I have seen,
tine dimensions are not discussed.  I don't remember ever seeing any
thing about overall length either.  The number of tines and the type of
handles are discussed. From personal experience I can say that
mid-nineteenth forks were general made of stamped steel.  The tips of
the tines are square but widen to rectangles toward the handle.  I
suggest that you check some antique shops or reenactor's supplies.  

Here are some references to help identify the right kinds of forks.
Dunning, P.
2000	Composite Table Cutlery from 1700 to 1930.  Studies in Material
Culture Research.  The Society for Historical Archaeology.  California,
Pennsylvania.

Moore, S.
1995	Table Knives and Forks.  Shire Publications.  Shire Album No.
320.  Princes Risbourough, UK 

Wade, B.
1979	Cutlery from the Roma Site, Prince Edward Island.  Roma Site,
Prince Edward Island.  National Historic Parks and Sites Branch; Parks
Canada, Environment Canada.  History and Archaeology 27.  Hull, Canada.

1982	Cutlery from the Fort at Coteau-du-Lac, Quebec. National
Historic Parks and Sites Branch; Parks Canada, Environment Canada.
History and Archaeology 61. Hull, Canada.

Coffin S. et. Al.
2006  Feeding Desire: Design and the Tools of the Table. Assouline
Publishing.  New York.   

Keith Doms