Throughout the recent years, several efforts have been conducted in studying Stirling engine which have yielded various models for analysis of Stirling engine thermal efficiency and output power. In the present study, the applicability of a combined Stirling and Otto cycle power plant where a Stirling cycle engine would serve as a bottoming cycle for a stationary Otto cycle engine is investigated. Output power of Stirling engine and Stirling engine thermal efficiency are optimized and total pressure losses of Stirling engine is optimized executing NSGA approach and finite speed thermodynamic analysis. The outcomes gained are satisfactory verified versus actual recorded data of Stirling engine. Decision making was performed via three well-known methods. Finally, error analysis was performed on the outputs obtained from this optimization.