I assume those new holes would need to be lower on the mag as well, otherwise it will snag on the original holes every time you insert the mag.
New Lower holes is worse. Then you've got to get past the higher notch when loading the mag or dropping it.
If the new opening ares are higher (nearer the top and away from the "stock" slots), or just a bit higher, you might be able to make them work. But, if the new openings are just a little lower, you'll probably be S-O-L.
That said, cutting openings in the mag body that are precise enough to properly engage the mag release and still hold the mag in the proper position is easier said than done.
Generally speaking, if the mags don't work in their original form (i.e., easily lock into place and feed rounds when the slide is cycled) it's very difficult to make them work with modification.