I have several of these on my cars. They are bullet proof. No Brushes, really simple regulator configuration (might just be a rectifier) and an excellent waterpump, with pulley ratios of your choice. They are essentially custom made for your application. John Barrett is the fellow that does them and he will make them with your choice of racing waterpump and in a variety of pulley configurations. I have on on my SBF in the mustang with 2 Vbelts, and on the RCR-40 with a serpentine and 60amp, and on a Big Block Chevy. They are generally 30 amp units, but you can get the double wide that is 60amp. Have run the mustang for several years on one without a problem.
Downside, cost. It ends up being a more then a race alternator, waterpump and pulley but you get rid of all the bracketing and makes for a nice package.
I can't say enough good things about it, but give John a call he is an old time racer and will chat your ear off!
Sandy