If "starting from scratch", the later cover/pump ('69-up) arrangement is considered the better one. Pulleys can be a real bag of worms. If you can find a "donor" car with all the brackets, pulleys, etc., you would be "ahead of the game".
If you're looking for "correct", the '68 cover is a "1-year only" part and pulleys are even more difficult to find. The '67 uses the smaller 2-piece balancer and the '69-up uses the different water pump.
FWIW
Jim