Convert pullover to cardigan

I want to make the [Storm sweater](https://www.ravelry.com/patterns/library/storm-sweater-3), but I want to convert it to a cardigan. Should I make it as is and then steek it, should I make a change to the front to set up the steek or should I just knit it flat somehow? I'm always getting myself into trouble when I want to change a pattern just a little bit …

I'm leaving on vacation next week and I need a new knitting project to keep myself from giving my husband driving advice. The yarn has already been wound into balls.