The Marmara's Sea with its near-field tsunami complications in Europe and the eastern Mediterranean, is paradoxically surrounded by a densely urbanised, infrastructure-rich coastline and positioned above the North Anatolian Fault system with historical earthquake events, submarine slope processes and narrow-basin resonance that impact coastal water levels. This fact motivated the current study presenting a benchmark-consistent GeoClaw modelling roadmap on seven historical Marmara tsunami scenarios selected from 22-event source catalogue with numerical comparison through 20-lane. The lanes represent exclusively, different source-construction, turning strategy, comprising earthquake-only, earthquake-plus-landslide, adaptive sampling, hybrid site-blend, and close-loop correction variants. From the first lane to the final selected best lane of the simulations set, the benchmark error could be reduced from maximum 1.93 m to 0.019 m in MAE (Mean Absolute Error) and 2.26 m to 0.024 m in RMSE (Root Mean Square Error), with all seven events cases remaining below 10 % error and the largest absolute percent error is 2.4 %. After target-based scenario selection, the corresponding outputs such as gauge-history, travel-time, and bridge-ready hydrodynamic outputs, providing a reproducible chain from historical source interpretation to infrastructure demand inputs are extracted. The workflow is designed for regions where instrumental tsunami records are sparse, but historical runup constraints, bathymetry, mapped faults, and scenario logic can be combined transparently.