Delphi Calculation Program Rebuild

The task is to reverse-engineer an existing Windows application written in Delphi, understand every formula it applies, and produce a brand-new build that replicates the behaviour one-to-one. I can run the original program on my side and will share the installer together with several trusted input / output pairs, so you can repeatedly verify that your rewrite produces exactly the same numbers, generates the same files, and keeps the original screen layout intact.

No source code is available, so you will need to disassemble, debug, or instrument the binary to uncover the full calculation flow. Once the logic is mapped, the goal is to deliver a clean, maintainable codebase in the language of your choice (Delphi, C#, or C++ are all acceptable), plus a compiled executable that mirrors the current program’s results and user interface.

To consider the project complete I will check:
• identical calculation results for all supplied and additional test cases
• identical input and output file formats, byte for byte
• a UI that matches the original layout so users feel no learning curve

Please outline your preferred toolchain (IDA, Ghidra, x64dbg, etc.), previous experience with Delphi binaries, and an estimated timeline from initial analysis to final build.