You can check out US Alternators. They built me a 330amp large case hairpin to my spec with clutched pulley (many HO alt companies use solid underdrive pulleys) and optimized regulator voltage that changes based on temperature. (ie +15v in sub-freezing and 14.4v in high summer temps.)
This was for my ALH golf, so I have no clue for your vehicle, but of all companies I contacted (Mechman, Singer, JS, etc) only US was able to build what I wanted.
Good luck with your HO journey. It is tricky to find a builder....