When installing the engine mount I had match drilled the holes in the firewall mounting stackup (bracket, brace, firewall, rib) to 5/16" but the bolts didn't appear to protrude perpendicular to firewall and the last pad on the engine mount was a bear to install. I found that one of the holes in the mount was burred so I reamed it with 5/16" drill bit. I redrilled the firewall holes to 21/64" to add a little bit more clearance for the bolts and to allow for positional tolerance. The mount fits very tight now, but I don't have to force the last pad into position. Good job!
