This is what you get for not paying close enough attention to the Twitter and Facebook updates of people you follow. On March the 8th earlier this spring, it was announced on Mingus' Facebook page (run by his widow Sue, I assume) that tapes for a Part 2 of the great 1964 Town Hall Concert featuring Eric Dolphy was being prepared for release. The message explained that the tapes had not been issued earlier as they (i.e. Sue and Charles) had ran out of funds after the release of part one, or what is just known as Town Hall Concert (1964). There's also a possibility for a Mosaic box set.
Read the full FB update here.