90 minutes will change the hop utilization so you may need to adjust timing of the recipe and amount of hops added. Also, the 30 minutes will save you from boiling off about 3/4 of a gallon of water, so be sure to account for that.
I did 2 brews yesterday, took 6.25 gallons of total wort and boiled for 60. Got exactly 5 gallons after dumping into primary.
Primary - Apfelwine
Secondary - Niagara white wine
Kegged - AH Special Holiday Ale, AH Cream Ale, AH Honey Wheat
Bottled - Continental Pilsner, Island Mist Mango Citrus, Island Mist Wildberry Shiraz
Up next - AH Foster's clone, Labatt's clone, Hard Apple Cider,
The Independence Street Brew House