isolator issue

The main issue is that the customer tells me he has money to spend so money is no object but im starting to think that maybe what he is asking for may be more of a headache then anything Confidence is the key to any project!!

Why a headache? You mean his choice of music? The alternator should fix the problem unless everything else is also undersized.... It sounds like a reasonably typical system. Install it, then plan it & design it and start again from scratch.

he ordered the alternator but what company would make an HO Alternator and how much is it more or less Confidence is the key to any project!!

If he's ordered the alternator, then I presume the company he's ordered it from would make an HO alternator or know of one that does. Often alternator manufacturers make HO alternators. Sometimes they also make standard or OEM alternators, though they may also make other products. As to the names of such companies, I would have to search using a thing called a googler. The last I found was a mob that made 200A or 400A alternators intended for welding which suited audio applications. Purpose built and not re-wound alternators. But your customer seems cool. If they have already ordered, then they are a loaded trial by error sort of a person with a spare vehicle etc (else not bothered by down time (no pun intended - Sydney's Downside played excellent music - Monkey comes to mind!)). That's great for the economy and the people they end up supporting.