If this helps you any, my 1974 FSM lists the following:

400 2bbl/440 std cam
260* intake duration .434 lift/268* exhaust duration .430 lift
intake opens (BTC)18
intake closes (ABC) 62
exhaust opens (BBC) 68
exhaust closes (ATC) 20
Valve overlap 38

400 4bbl/440-HP
268* intake duration .450 lift/284* exhaust duration .464 lift
intake opens (BTC)21
intake closes (ABC) 67
exhaust opens (BBC) 79
exhaust closes (ATC) 25
Valve overlap 46