The hops are all late boil (in the last 20 mins) so I wouldn't worry too much about subtle AA% differences, especially with the 10 and 0 minute ones. If the AA%'s are double or half then you may want to adjust the 20 min one.
P.S. A lower ABV 'sessionable' version of this beer is available too - see here
. This is the one I keep on tap all the time now. At only 4.3% ABV it's more approachable and doesn't give anything up in terms of flavour.
P.P.S. Agreed with Gnomebrewer on the hop substitutions. While I love Columbus, it's a bit out of place here and will overpower. If you want to use it, I'd recommend my Green Flash West Coast IPA