I think most everyone here understands that a 302 and 5.0L are the same engine, and I don't have engineering drawings of the SBF 302/5.0L heads, but I chased header flanges through a lot of sources and ended up buying a pair from Stainless Headers Manufacturing, Inc out of MN - 3/8" thick and precise fit stock ports for $74 delivered ($29.95 each and $13 shipping March 2010) http://www.stainlessheaders.com/flanges He has flanges for all heads, either stainless or mild steel, and he knows his business. Headers by Ed is another place that really knows their heads - http://www.headersbyed.com/ Both Summit & Jegs also have flanges, bare or stubs, with prices ranging from <$50 to $150. Hard to believe you can make a set cheaper than you can buy them today, but I may not understand what you're doing.