I may be over thinking this I don't know.

In the case of an out of square post (also roughsawn), if I want to house my intersecting beams on the non reference faces, should I measure in equal distance (say 7.5" on an 8×8") from the reference faces instead of measuring in 1/2" off the non reference face.

If this is the case I'm also assuming I can't use a skill saw to the full depth to cut the housing if the timber is out of square by a 1/4" or so? My thinking is I will have to cut it to the shallower depth of the two sides and then work it down with a chisel so that each beam comes off of the both sides of the post in line with eachother. I'm also assuming this will require shimming my mortise machine so that it will be in the same line as reference face mortises?

Another question, If I want to house my braces in the center of the post on these out of square faces, what's my best solution? I'm considering shimming a router template in the shape of the housing joint to be parallel to the reference face and routing it out but would welcome tried and true solutions.