Steve, I don't know if he builds complete engines but you might call Fox Valley Hot Rods at 847-382-3089. It's run by Matt Werksman, Cotton's son, and if he doesn't build engines I bet he will know who to see.
Larry
Mike's Automotive in St. Louis and Millstadt, Illinois they have lots of flathead experience. Also you may check with Effingham Re-Grind.
Wish there was some in Texas