You can run either pump.
What parts do you have right now for your front drive set up? Which alternator mount and which PS pump mount?
Maybe post some pictures if you are not sure and someone will help you identify them and determine which pump to get.
As for the balancer it makes no difference which one you have, the pully mounted to it will matter though.
If you don't have any of the front drive set up yet, you can run either pump (would suggest the short one if clearance will be an issue with the radiator) and buy your mounting brackets and pullys to match.