Distributed optimal dispatch strategies are attracting attention to exploit the fast and continuous control capabilities of converter-interfaced small-scale generators connected to power distribution systems. However, their impact on the supporting cyber structure and their scalability to ensure real-time performance need further study. In this paper, a proximal Jacobian distributed optimal power flow model for the dispatch of converter-based power distribution systems is proposed, which features a favorable convergence behavior. A suitable cyber architecture to realize such model is developed through this paper. The corresponding cyber costs are quantified and the proposed architecture's scalability is analyzed through numerical experiments.