Timber Framers Guild Forums General General Forum Questions Which side of the beam to mortise?

Is it better to cut a 1" mortise into the (a) inside of center cut beam or (b) the outside. In the case of a boxed heart beam, they are both
the "outside" (c & d)

The beam is an 8x12 (7.5" x 11.5") and the mortise is for 6x8's (5.5" x 7.5"). The wood is Coastal Dougfir, #1 and structural select.

Thanks in advance,

-srj