If your going to bother having something machined, then either get a new arbor or a new bushing machined that will fit on your current arbor's threads. I just cannot see why you would want to buy a 1" arbor and machine it smaller to fit a bushing to get up the a 1-1/2" hole??? Then you could also hove your 30mm blades bored out for the same 1-1/2" size. That is if you needed more the 50+ blades on hand??

BTW, how big is your shop? Over 150 blades is a LOT of saw blades

Heck if you sold 1/4 of them you would have plenty to cover the cost of machining!

JeffD