I am in the process of duplicating a set of HBK II main rotor blades out of wood. I chose popular just cause I had a piece on hand, and it is fairly strong. However the weight seems like it will turn out slightly heavier than the stock blades. Should this be a problem?

welcome to RCU, nope shouldn't be a problem. I've flown blades up to double the weight of the stock blades on the blade cp pro, wasn't a problem at all. If you are running the stock brushed config instead of brushless, it will put a load on a motor that is already over stressed, and it probably wouldn't be good for that. If you don't have brushless yet though, I would really consider it.