Recent progress in hollow-core fiber (HCF) technol- ogy is raising the prospects for the deployment of this type of fiber in future infrastructure upgrades. Although earlier deployments of HCF will take advantage of its low latency property to realize point-to-point links (e.g., in the metro and aggregation network segments), HCF generations with better specifications (improving performance and deployment robustness) may become suitable for more demanding regional and long-haul network applications. In these scenarios, they may co-exist with traditional fiber types in order to ensure, at the network-level, an appropriate balance between latency reduction and the increase of capital expenses associated to both the higher cost of HCF spans and the potential reductions in reach. Therefore, fiber infrastructure owners will face a new design problem, which consists of optimizing the spans where HCF is to be used to minimize service latency while meeting optical performance degradation and cost increase bounds. This paper describes an optimal method to solve this problem, by leveraging the approximation of incoherent accu- mulation of noise to derive an integer linear programming (ILP) model, and two variants of a heuristic algorithm. A set of detailed simulations over a reference optical transport network highlight the optimality and scalability of the proposed method.