Kevin,
If I'm right, didn't Ford / Mercury run the FE 427 well into the '70 NASCAR season? I believe this was due to the 385 series engines taking a bit longer in development than planned. I think they also continued to run the '69 Talledega / Cyclone Spoiler sheetmetal in '70 due to their superior aero.
Love that picture of Cale!
Bruce
Yep, that smile on Cale is the smile of a winner!
And yes, the teams were given IIRC a choice of running the then new Blue Crescent (remember that name fellas?) Boss 429 engines or the tried and true FE Tunnel Port engines. Later, Ford again IIRC sent down an edict, after the Boss was track proven, to stop using the FE in at least the NASCAR's big track/asphalt racing. The FE's did well for some years there after in dirt track, short track, state fair competition.