We propose an F2F 3D-IC placement framework for heterogeneous dies that integrates in-placement flipping via the Flipping Weighted Average Wirelength (FWA-WL) model. By embedding flipping into the wirelength objective, it jointly optimizes cell/macro locations and orientations under die-specific constraints. On the ICCAD 2023 Contest Problem B benchmarks, it achieves up to 5\% HPWL reduction when combined with multi-die concurrent placement.