I have been down this road. At the end - you may go to Africa. If you want a 404 Jeff, then you have one built, modified or find a good used one. There is no inexpensive option. If you can afford to hunt dangerous game, then you can afford a .400 Jeff by Dakota or Parkwest or someone. These are out there but are not cheap.
Ammo runs $10 per shot or more, so if you choose not to afford one, buy a .375 HH or .416 Rigby or Rem and enjoy the hunt.
The hunt is not about the rifle, it is about the experience.
No carpenter has a custom hammer and has it in the pics of his house. Same with guns in the pic with your buff or lion.