I went the opposite direction. I put my stock in a mill and used an end mill to cut a recess in the stock so that the lug would fit. The aluminum is very thin is that area of the bedding block and you will actually remove some composite material as well. One of the reasons I went this direction is that the new lug was also wider and so I was going to have to remove some material any way.
I would recommend taking it to a gunsmith or machine shop and have them do it for you. Cost on that would be minimal and everything would be uniformed.
Otherwise, you could get a carbide cutting tool for a dremel style tool and do the work yourself. Check the depth with a dial caliper from the bedding block to the bottom of the lug recess and then compare that number to the depth of the lug to reciever. Subtract the two and that is the cutting depth needed.
I would also have you consider skim bedding the action and lug area anyway. None of my HS stocks made very good contact with the actions. The worst one had less than 10 to 15% contact along the entire action. If you are handy, then there is a wealth of information on this site as well as other sites on how to skim bed an action. Otherwise, have a gunsmith do it while he is doing the lug.
I just don't like the idea of messing with the nice, pretty new lug.
Hope this helps and good luck.