In looking at the 1965-72 MPC, as noted above, the Distributor you note should be a Single Point Distributor, for Fairlanes and Mustangs with ST,v Carb, and Imco Emision System. There is no Dual Point Distributor Shown for 1970, 351's.
For 1971, the Dual Point Distributor is shown for Mustangs with 351 Cobra Jet, ST and AT, with 4v (Marked D1ZF-12127-BA, Part # D1ZZ-12127-B or E), for Boss 351 with ST and 4v (Marked D1ZF-12127-DA, Part # D1ZZ-12127-D), and for 351 Mustang with ST and 4v (Marked D1ZF-12127-EA, Part # D1ZZ-12127-E).
Hope this helps.
Bob