Is this concrete suitable for conduction into mother earth or should I run
a large copper strap from the pole to an earth rod?

Hi Jerd,
The latter, and you should have more than one if possible. The strap should
not have bends in it, should be low inductance (a copper strap is better
than a wire, etc.). Remember there are zillions of electrons coming down
that pole, and they all have to get into the earth, and all the ones in
front are being pushed by the ones in back, all screaming "Hurry up, or get
the hell outta the way, cause I gotta go...... real bad." And if they don't
get outta the way, the ones in back will jump around them like a New York
driver in a traffic jamb, to find a faster way to get where they are headed.
And you don't want that to happen because the other path may be through your
coax and into your house/equipment.
Now how does that portray the situation? That's the best I can do !

Rick K2XT