You will have to optimise some damages parts into an FBX, middle definition scan. ( a photogrammetry ).This job dont need to change, or optimise any meshes.The job is to impact the texture, but not from photoshop, you will need to work on the volume,
with Zbrush, or painter.
Here are the problematic zones.
A pro under Zbrush, can do all this in maximum one day.
The scan of 30GB will be transfered to you after the signature of an L.O.I.
You need to have at least, a big PC, with i9 CPU and 4090 graphic card.
See below :
