Going on JUST this info...
"Player A makes his 8 in the called pocket, turns to player B and shakes their hand for the good game. Whilst shaking hands and chatting the cue ball continues on it's path 3 rails and fouls in the same pocket the 8 ball was made in.
Who wins, Player A or B and Why?"
PLAYER B WINS.
The handshake can be construed as a win or loss to Player A. It is only until all balls have stopped rolling is game over. The info given is incomplete IF something else happens we know not about.
Further question via same scenario.
8 drops, cue rolls around table and stops just short of dropping into the pocket. Handshake commences and several moments later cue-ball drops into the pocket. Who wins?
E. PLAY
1. If a shooter inadvertently pockets his opponents ball, it remains down, however, if the shooter does not legally pocket one of his own group, he loses his turn.
2. Each player continues to shoot so long as he legally pockets any of his object balls (Exception: calling a safety). Should a player fail to pocket his designated group ball, he shall lose his turn.
3. If a player fails to hit the 8-ball while shooting at it, it is a foul and the game continues. When the 8-ball is the legal object ball, a scratch or foul is not a loss of game if the 8-ball is not pocketed or jumped off the table. Incoming player has cue ball in hand.
4. In the event the cue ball or an object ball stops on the edge of the pocket then falls into the pocket because of vibrations, fan or stamping of feet, it shall be replaced on the edge of the pocket as near as possible to its position before interference.
Fair question, it seems the Cue ball would spot up and player A would be the winner in your scenario as per rule #4 but is trumped by rule #3.