[Jac Mac]

If the drilling's extend virtually down to the gallery for the lifter bores, but for some reason have not been 'broken thru' into that gallery then by using a very slow drill it might be feasible to do just that aided with magnets, shop vacuum, etc to catch the chips. Still scary though, only takes one chip to find its way down to a rod bearing to ruin your day. Not worth the risk IMHO.