You know, if it was me, I would still use a keyed hub in addition to the Locktite RC680. The Locktite is primarily designed for radial loads, such as are encountered when you are trying to make up for an improper fit of a bearing on a shaft. I don't think it will stand up to torsional loads like you have on the hub.

 

If it were me I'd rather tear it down and replace what looks to be a dodgy crank with something better. Yes, that sucks. But how much worse would it be to blow it up and have to replace the other new parts?