Engine Code Help

[Brads71C10]

Trying to determine what year 350 I have in my 66. Here are the #'s I have:

K09 13 CMR
K = Engine Plant St. Catherines, Ontario
0913 = Sep. 13
CMR =
1978 350 m/t L82 4sp 220HP 4 bolt main (Corvette-Z/28)
or
1974 350 a/t 145hp (A body)

Here is the # on the block: 3970010 = 69-79 350
Here is the Intake #: Intake: 346250 GM 305/350------- 76-82------- 4-Brl Quadrajet flange

Now...how do I find out if I have the 74 or 78 350? Are there other #'s I can try to find and reference?

Any help would be greatly appreciated.