Slant 6 build date

G'day all.....I picked up a 225 slant 6 today, and was wondering if some-one could tell me what/when it was made.
I'm having a guess at 1968.....????
It still had a genuine water pump on it, and I had to put an ocky strap on it to stop it spinning......had a round trip of about 70 miles to go get it.
There wasn't any manifolds on it, just the dizzy, oil pump and pipes + filter mount, alternator + brackets, harmonic balancer, water pump + pulley + fan, fuel pump, and the rest on the back of it.

Awfull clean motor. Someone has been in there before you.