Hi - Westtown is about 1 hr 40 minutes drive from New York City and is said to be very beautiful. There was a publication done in 1930 that listed all the Presbyterian church burials in the cemetery, which is too early for your needs. Findagrave doesn't seem to update this much, if at all.
Here is what has helped me find death/burial info on relatives in small town USA: 1) check for newspapers in the local area. New York State Library in Albany has microfilm of many older Orange County papers (Westtown and nearby Minisink don't appear, but there are some from Port Jervis); 2) go to funeral homes and Presbyterian churches still extant in the area. Sometimes they will have records inherited from their predecessors; 3) wander around the cemetery. Orange County has a relatively small population and the whole county had only ~135K people in the mid 1930s. The cemetery might have as few as 300 graves.
At the very least you should be able to obtain a death certificate. During this time-frame I believe death registrations were with the county, and probably a requirement to send a copy on to the State. Here is a link where you can order a death cert for $22 since you know the exact year:
http://www.health.state.ny.us/vital_records/genealogy.htm Nick
