I've just been using the standard cloth covered plug wire that can be bought at most engine shows. Working OK. Most magneto shops should have some.
NAPA usually can get a solid core wire, Packard 440. Magnetos require plain solid core wire and also non resistor plugs. The antique car, tractor, or engine places usually stock the solid core wire with a nice period cover on it if you want the original look.
Go here
http://brillman.com/index.php?Cpath=25_58
solid core wire from napa - part #734803. 59 cents a foot last time I bought it. - Wally Terminals 727008 (4) 727006 (4) and 4 boots#727402
Hey Brewser what about the boots?