Steve2 mentioned Ray Franz. I don’t believe he was tight-lipped about the organization’s finances. The Governing Body and Watchtower is siloed into committees. Ray was in the Writing Department. He wasn’t part of the committees or departments that delved into the financial side.
Besides any intell he had on the matter would be nearly 40 years old now. So much has changed, both in the Watchtower and in the world.