For a street car where you’re not worried about much of anything, you could make a blind choice of a 3500 and it would work. While I wouldn’t call it a great choice. When you call up a place for the converter to be custom built as per your specifics and hopefully a dyno sheet they can see, they’ll know just what to do for best results in the specific application your telling them on what your doing.
You and your best bud can build identical engines but use them for different things, like absolute street driver for you and track only for your buddy, you’ll get two very different converters!
The more information you supply the better the result. Hide nothing, tell all, no secrets from your converter guy. You’ll forget the price paid though the years of excellence in service in your car. Guarantee it.