Help - Engine type based on engine number?

[nqld911]

Hi all.

My 911 is getting close to rebuilt. To complete it I need to find out the engine type.

The number is 7318935.

I dont understand why the first number is a 6, and my interpretation is as follows

7= 6 = 6 cyl.
3 = ROW or Japan. 4 = US
1 = year 1981
8 = Japan
935 = seq. ser. no.

1981 Japan 3.0SC engine type 930/17 180HP@5500

Can someone confirm this for me? ie that it is a 930/17?

Or is there another way of telling which 3.0 litre it is?

Thanks

James