I don't know for sure because I've never tried it, but the exhaust port diameter and spacing may be the same on the SOHC 750 and the DOHC fours. I have a Jardine exhaust on my '75 750F. When I bought it, Jardine listed the same exhaust for the SOHC and the 750-1100 DOHCs. Their website currently lists the same exhaust to fit 75-78 CB750s and the 80-83 CB900Cs. I don't have a DOHC Honda around anymore to check it, though.