Hey Don, sounds like you might have tackled the engine ID for this one, if not here is a goood link http://www.fordification.com/engineIDtags.htm
and here http://www.fordification.com/engineID.htm
The block should be stamped with a number like C8 C= 1960's 8= the specific year of the 1960's in this case 1968.
and you should be able to see the block casting # on the side as shown herehttp://www.aacncclub.com/FORD_BLOCK_CASTING.html#390fordblock