Well, I know it's not exactly the same, but when I geared up my Ninja, (all 300lbs of it), I went from 14/45 to 15/41. First gear felt roughly the same taking off, though it did have more to go before it ran out, but 6th was difficult to use on hills.
I'd say go for the lowest set of gears you can find, you can always shift down.
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