The design of compressors for high-temperature heat pumps is inherently a multi-component problem. Conventional textbook methodologies adopt a decomposed, sequential strategy in which individual subcomponents are designed and optimized in isolation. Current preliminary design approaches optimize impeller aerodynamics using mean-line models with empirical loss correlations achieving 5-10\% accuracy, while rotordynamic analysis of the shaft-bearing-impeller assembly occurs after aerodynamic geometry is finalized \cite{meroni2018, schaffrath2022}. Optimizing components separately leads to suboptimal assemblies where aerodynamically efficient impellers create rotordynamic instabilities or bearing load violations, resulting in costly design iterations when rotordynamic constraints conflict with aerodynamic objectives. While coupled aerodynamic-structural optimization has proven effective \cite{shouyi2019, schaffrath2025} for single-component designs, integrated multi-component assembly optimization considering aerodynamic-rotordynamic interactions at the preliminary design stage remains unexplored. For compressors, early integration of assembly-level constraints natural frequency placement, critical speed margins, bearing load limits, and impeller-shaft interface requirements with aerodynamic efficiency optimization is critical. This work presents an integrated framework coupling in-house aerodynamic and rotordynamic preliminary design tools. Multi-objective evolutionary algorithms simultaneously optimize impeller geometry, shaft dimensions, and bearing locations to maximize isentropic efficiency while ensuring adequate critical speed margins across multiple operating conditions \cite{li2017}. Pareto-optimal fronts quantify trade-offs between aerodynamic performance and rotordynamic stability, preventing locally optimal but globally suboptimal solutions. Preliminary results reveal that integrated assembly optimization identifies non-intuitive designs where modest aerodynamic efficiency reductions enable improvements in rotordynamic stability margins. Pareto fronts quantify assembly-level trade-offs, providing designers with feasible multi-component solutions early in the design process, reducing late-stage redesigns and enabling informed component selection for high-temperature heat pump applications.