In the campaign that I run, we also use the "Skills and Powers"
rules. In cases where very specific rules have been set out (ie.
specialty priests, paladins, etc) we simply used the classes as set
forth, and modified the race, etc as the character saw fit. One
piece of advice though. Beware of allowing players to get too high a
strength score. In our campaign I have to deal with a dwarven
fighter/priest with a 20 muscle (ack!) Not the easiest thing in the
world to find a foe for him while not slagging the rest of the party.