JW,
You cannot go wrong with a McMillan stock. IMO they make the finest fiberglass stocks available. As to the Lazzaroni thumbhole it will be a bit heavier than some of the other offerings by McMillan.
I know the designer of both the Lazzaroni stocks, Randy Lawson of Harry Lawson Co. in Tucson Az. John Lazzaroni, also from Tucson, came to Randy to have him design two stocks that would dress up his rifles and help control recoil. Then he had McMillan make them.
The thumbhole design original was designed by Harry, Randy's father back in the 60s. The wooden stocks are very light and have a variety of features that make them point fast and control recoil.
I would say yes to you making a rifle aound this stock with your 280AI.
A friend has the Lazzaroni sporter stock with a 257 weatherby and loves it.
Hope that helps.