I hate to be the contrarian, but I don't see why it's urgent that he should change the 53-39. His 60 cadence isn't all that problematic on a hard climb, but you could gain a little (for a lot less) if you can find a 12-30 cassette. A short cage Shimano RD might (likely could) be pushed that far, if not they're not that much if we're talking 8- or 9- speed.

I just wouldn't want to push him into a compact if it wasn't really needed. With his size and room for improvement ("recently got into" it) he might be spinning up that grade in a few months.