Thanks William for the idea to look for other places in the car that used the same fastener.
I looked at the Z10 I am restoring last night. A lot of stuff on it has been messed with over 50 years, but I am pretty sure these places had not been touched. The plastic gas pedal bushing and the steering column all had the same 4 screws that Pete showed, but with an E on the the head.
Now to convince the Legend Judges you don't need the small bolt with the big washer on the radiator shroud...
Mike