I am about to drill those four rivet holes, apart from keeping the four builder drilled holes inline with the rivets in the I-beam, are there any other dimensions such as spacing, as I cannot find any?

The manual does not say to mix micro balloons with the Hysol on the spar strut fittings but it does for the spar reinforcement fittings and when dissimilar metals are used, is this just a typo omission or do they not want micro balloons in that joint?

Paul