How rowdy? No offense meant, but that's kind of a hard metric to pin down, especially in the absence of any info on other modifications. But I'll take the question to ask if you'll get enough giddyup out of installing a Shell #1 cam in a 650 at stock displacement to justify the time and expense.
If the camshaft is the only thing you plan to change, then no, it's not worth it. For the cam to be effective, the motor has to be able to breathe, and that means relief at the intake and exhaust ends, and that entails mechanical carbies in place of the vacuum carbs, because vacuum carbs don't perform their best without a still air box and the air box on the XS650 isn't big enough. The biggest bang for the buck will be from Mikuni VM34 round slides from a reputable vendor, and that means 650 Central or Hoos Racing. Another thing: if you've been reading that godawful Minton article, do not believe him when he claims that stock valve springs will work with the Shell #1. (Well, they'll work, just not for very long before you wind up cupping a valve.)
Other needful things: either have the head ported by somebody who knows that you can't make power by hogging out ports that are marginally too big to start with, or just knock down the casting flaws yourself and call it good. And bump the static CR a bit; you should get to around 9:1 or a tad north of that by dropping the deck by around .020" with a thinner head gasket. If you don't know how to check valve to piston and piston to squish clearances, Google is your friend. Lonnie Visconti at Copper Gaskets Unlimited can help you with the head gasket; Google for contact info.
Of course all of that work will be wasted if you don't degree the cam in right, and the way the available units are ground, that's a bit of a challenge. What's worked best for me is to go for 45* exhaust opening. Other procedures have led to a lot of short shifting due to advanced valve timing.