olywa: I just checked the slides for my 70S in 380 and they have a fixed front sight cast as part of the slide. A gunsmith would have to weld a spot on your front sight and then work it down to get poi to poa at whatever distance you preferred. But, he should add enough material to get poi to poa with the rear sight at its mid-point.
All that being said, he would have to be good at it so as not to ruin the looks of the slide and sights.
I recently obtained a 2nd complete 'upper' for my 70S in 380. At first it wouldn't fit my frame until I stoned the barrel channels, then had to stone them a 2nd or 3rd time to get the piece to shoot to poa at 25m, and then it was fine. You might try that route to see if you can bring the poi down a couple of inches at 25m. Any of the work you had completed would not be visible. HTH. Mikey.