Well, out of stock is hard to get past.
I know at least one respondant here (with a locomotive as his avatar) does conversions of Model A generators - the regulator is internal.
Another is mentioned at Vince Falter's site. He highly recommends one that is built on the "band" which covers the outboard end of the generator. See
http://www.fordgarage.com/pages/generator.htm
I only name "show car" as some sort of standard. Many of us attempt to emulate "show appearance."
Joe K