Obviously interference fit gives a better hole filling factor, but it should be noted that Hi-loks are not preferred for interference fit/fatique situations. Note that radius-lead-in type fasteners are preferred for interference and fatigue (see Hi-shear fasteners like Hi-lite's). If I remember...
I didn't see a previous posting of a free access site for mil hdbk 5.
Here it is posted... along with other mil spec's.
http://combatindex.com/mil_docs/mil_hdbk_index_01.html