Alright, I've been doing math. I would say stick to ending up with 47 sts after the decrease row, which means changing the number of sts cast on. If you stuck to the *k2, cast off 2 pattern, you would have to cast on 91 sts, which seems ridiculous. If you opted to *k2, cast off 1, you could cast on 69 sts, which sounds better. You would have to add an extra knit stich to make it come out to 47 sts. So after you cast on, your next row would look like this:
*k2, cast off 1. rep 11 times. k3. cast off 1. *k2, cast off 1. rep 10 times. k2
If you k2tog instead of casting off, you would need to cast on 62 sts. Then your decrease row would look like this:
*k2, k2 tog. rep 15 times. k2.
Now, I'm fairly new to all this and someone may know better than I. But this is the best I could figure. Good luck!