Found! 6-19-68 340 engine block.

Not correct. There were red 69 340's until the TSB came out on September 9, 1968 saying all 69 340's are to be turquoise (same as the big blocks) until somewhere in 69 when some were painted a darker blue. No TSB has been located for that yet. Also, some late 69 340's have been rumored to be orange, but no TSB exists for that either. This has been beaten to death over the last 20 years...