Since I posted this thread I have been doing some googling of the subject... I'm leaning toward leaving my 28 unaltered at this point. Not finding much in the way of shops that advertise such a service so far, and results from various forum posts seem to indicate that a shop that would do it and not hurt the value of the piece would cost almost as much as finding a descent m57...
If I was looking to snubby-fy my 28 it might be worth looking into more seriously...But I want to keep the barrel as it is. I don't care for the idea of boring the barrel and installing an insert either.