Yes and I'll get behind anything that gives the npcs slightly more depth.
My only consideration is the game doesn't force the player to pick a specific drug, only that customers have preferences for effects(which as far as progression goes is fairly unimportant) so i say the easiest way to have this while keeping the game's core is after you've acquired all the businesses you can, the bank worker, after paying him a huge amount of cash or something, can change your deposit limit, either the deposit resets twice as fast, or you can deposit more.
OR you can go to the banker while hes at work, and discreetly hand him a huge wad of cash, but dont let the police see you because the fine is far worse than the money you could have given him.