Someone at rimfireforum.com should be able to help you.
The Winchester Model 68 bolt action single shot .22 was made from 1934-46. It did not have a rear sight mounted on the barrel, but had a receiver mounted Winchester No. 96A peep sight (books at $20-40). As options, Winchester offered the Lyman No. 55W or 57ES Receiver Sights ($25-75). The hunt for old gunsights can pretty interesting. Lyman is still in business, and may be of some help. Good luck. By the way, the rifle (with sights) books from $275 at 100% to $50 at 60% condition.
The address of the Lyman Public Library is: 313 Jeffers Street, Lyman, 69352 0384
The address of the Lyman Branch Library is: 204 E Sage, Lyman, 82937 0839
Lyman Potts's birth name is J. Lyman Potts.
Follow instructions in owner's manual. Take it to a gun shop. Get a manual from Lyman.
Princeton Lyman was born in 1935.
Lyman Viaduct was created in 1873.
Lyman Sherwood was born in 1802.
Lyman Sherwood died in 1865.
Lyman Paine died in 1978.
Lyman Paine was born in 1901.
Lyman Parks was born in 1917.
Lyman Parks died in 2009.
Eric Lyman was born in 1965.
Lyman Heath died in 1870.
Lyman Heath was born in 1804.
Job Lyman died in 1870.
Job Lyman was born in 1781.
Phineas Lyman died in 1774.
Phineas Lyman was born in 1716.
Daniel Lyman was born in 1756.
Daniel Lyman died in 1830.
Lyman Tremain was born in 1819.
Lyman Tremain died in 1878.