Roy,
I think that "1163 of 1864" means the one-thousand, one-hundred and sixty third patent issued in 1864.

Just how long Powell continued to build their No.1 Patent action -- the lift-up lever, is unclear. One source suggests that the last one was sold in 1921. Between 1864 and 1895 they built slightly more than 3000 or about 100 per year.

The "Powells Patent" number that I am looking for represents the patent use (total number of that action made to that point). It should be stamped on the action flat under the barrels.