My understanding is that Stans Headers (also in Washington state) does make the headers for FPA, however, the headers they build for FPA are propietary, and FPA headers are only available from FPA. When I ordered the FPA headers for my 59, I had my choice of several header flange configurations, 8, 14, and 16 bolt exhaust patterns, with high or low exhaust port locations. So as long as you give Stam at FPA your correct head information, there should be no port mis matching. Plus the flanges are thicker than average. I don`t know if FPA has finished headers on the shelf, when I ordered mine, it took a few weeks from ordering to delivery. The headers even had my name and build date stamped into the flanges. Prehaps FPA may stock more common headers, like say 67-70 Mustangs with CJ heads, but my 16 bolt CJ headed 57-59 Ford car headers are likely not one of their big sellers.