I decided to get the car, I'll be picking it up in a few weeks because i'm going on vacation. The transmission does have the flutter problem so i will be replacing the solenoids most likely.

 

The M54 on the E60 has an external expansion take, not close to the rad, and it doesn't fail on the E60 like it does on the E46. But the rad is a stupid design and gets clogged with stuff at the bottom and rot.
Easy enough to replace. The waterpump is a no brainer to replace and easy / cheap.
I did thermostat and waterpump when I picked up my car at 182k miles, now I just did 3 coils, plugs, valve cover gasket and grommets at 194k miles, next will be the oil canister gasket.

Check the DISA valve also, well known issue on the M54. Not the most powerful 3.0 but very reliable.