That book would still be a decent starting point, but you’d definitely want to do research about the specifics of whatever route(s) you select — mostly to find out about damage from fires or trail status (some might have been abandoned or damaged over the last two decades).
The most recent book I’m aware of that might be useful is “100 Classic Hikes: Montana” by Douglas Lorain. It has several hikes in the Bob Marshal Wilderness, but they’re mostly shorter trips. That said, it would be useful if you’re doing those trails as part of a longer trip and I think some described options for longer trips.
Guidebooks for a lot of places seem to be becoming more out of date with fewer revisions and new guidebooks published. The guidebook industry isn’t as profitable as it was a few decades ago and people (especially newer and/or younger hikers) prefer to seek out information about hiking and backpacking online rather than from guidebooks. One downside of this is that people tend to be more likely to go to the most popular places since there’s more information about them.