Bob, the only three C9 casting numbered starters are the BOSS 429 C9AF-A, 390cid C9AF-B, and the 250cid six cylinder C9ZF-A. The 250 starter would work but is not technically listed for a 351cid, like the C7AF-B. The other two, as you know, won’t work at all. Even the ‘69 BOSS 302 used a C7AF-F, which was carried over into the 1970 model year when replaced by the D0AF-C around January 1970.