I'm not sure if this is still available from the O&W historical society or if an updated version is available.
A Guide To The New York Ontario & Western's Monticello, Port Jervis & Kingston Division by Charle M. Breiner and William E. Scott - 90 pages with many photos, maps, structure plans and drawings of the railroads Monticello, Port Jervis & Kingston Division. This street by street guide will help you navigate along the right-of-way pointing out the remaining points of interest as you travel along.................................................. $15.00
Your best best would be to join and post on the O&W facebook page.
https://www.facebook.com/groups/OWRHS/