This type of thing caught my eye...but the doses in supplements are in the 500-1000 mg per day range and many people still say those supplements aren't that great. I don't think the epi content will hurt. It probably has a lot of health benefits.
Is it dosed high enough to be a reliable muscle builder? I doubt that. Maybe it will help a little and be a nice side effect, but eating a pound of cocoa every day doesn't seem like a good idea to me...even I have limits.
I've seen other estimates showing roughly 0.1% epi content in cocoa powder. This means that 98 mg figure you have is maybe 50 mg and probably going to vary in between there given each batch, different brands, etc.