There is no such thing as a classed official org.
Any official org (not a Franchise or Gung Ho group) can perform and teach any Class or Grade up to Class IV.
This includes Standard Dianetics HDC and HDG.
ONLY an official org can teach Academy Courses and qualify students for Scientology certificates.
HDG can ONLY be taught by an official org. (This qualifies Supervisors to teach HDC elsewhere.)
Dianetic Certificates can only be issued by an official org even when the course is taught elsewhere.
The difference between an official org and a Franchise or a Mission is that an official org is looked to as a distribution point for source, runs on policy, is responsible for its area and looks to its Continental Org and WW for policy.
It maintains the quality and standard of tech. It sets a standard for instruction.
If it maintains its ratio of Admin personnel to Tech (auditors and supervisors) on a 2 Admin maximum for every tech person and inclines toward I Admin to I Tech, and promotes well, maintains a professional image, develops no backlogs and delivers excellent service and cares for its field with ARC it should be far better paid and more solvent than any Franchise.
The idea of a "Public Division Org" is not very good. It is far better to develop a full org as in LRH ED 49 INT, Organization Program No. 1.
So long as an org functions crisply with the services it can deliver and defends itself as per Assistant Guardian actions, it can become very prosperous, serve its community and do its large share in bettering the community and doing its share in clearing the planet.