Here's three dealers that I have used in the past.
Terrill Machine Flathead Parts 254-893-2610 (TX)
Roberts Motor Parts Parts
http://www.robertsmotorparts.com/index.html Kanter Auto Parts
http://www.kanter.com/ Andy Bernbaum Auto Parts Parts
http://www.oldmoparts.com/ Terrill Machine had good prices on certain engine parts.