UPDATE (June 2020):
As of June 9, 2020, LTS has instituted Alma Brief Level rules allowing Alma to automatically exclude records from publishing in OCLC if they lack certain elements (see LTS Alma Brief Levels wiki page). However, if a record is exported from OCLC into Alma during the acquisitions process (i.e., awaiting full cataloging), the existence of OCLC number in the record trumps the criteria listed for exclusion so that particular record will push out to OCLC during the iterative Data Sync process. In that instance, you will still need to include 914 manually.
NEW IMPLEMENTATION (April 2020):
Starting April 13, 2020, Harvard Libraries will be implementing the use of new MARC field 914 in bib records as part of the OCLC Data Sync project. This new field will prevent a bib from being reported to OCLC through Data Sync and will replace the use of 908 in holdings. Houghton will adhere to this practice and discontinue the use of 908 in holdings while adding 914 to bib records moving forward.
...