You guys are talking about 2 different sets of headers. The 78500 headers are for a small block. The headers on BigBlockDart are 78070 which are for a big block in a b-body that they actually tried to use in an a-body. According to the application page in Summit they will fit a Dart from 67 to 76. I would try it, the worst that can happen is sending them back or selling them to get your money back.
