Hello Brian:
repairs to your posts can be done in this way:
Use a half lap of about 20 inches in length, and then either bolt the connection or if you want to keep things authentic bore 4 --1.5 inch holes and attach using oak pins split from good straight grained oak sharpened. You should use a drawbore technique on the holes ie: bore the holes out of alignment about 1\4inch to pull the joint tight tightly together. also the holes should not be aligned with one another but slightly out of line for good workmanship.
NH