I think you need to use MSG by taste. If you are too heavy handed, your stock will wind up tasting more dashi-like...probably something you don't want in a stew. If you are new to MSG, to get a handle on it do a bit of a taste test on the end of your finger. Compare salt, MSG, and a salt/pepper mix. When you understand the taste perceptions, you can better season your final product. By the way, you can always add more once the dish is complete...you can't remove too much.