Since the block size is small, I am going to assume that you would be using 1" finished logs. The problem is, if the center is also 1" then the center won't really be in the center of the block, because there will have to be three 1" logs on one side of the center and only two on the other side. I don't know if you have any requirements other than it be a log cabin, so one solution to keep the center in the center is to make the center block 2" finished.
Edited (after I looked at my pictures) - the first picture should show the red center moved down on, and where it is there would be a light color. This would maintain the stairsteps in the log cabin. But notice that the center is still off-center.
Last edited by dunster; 06-03-2015 at 12:42 PM.