Doug's suggestion is not for the faint of heart.

There used to be an ACCPAC addon (it may still be for sale) that allowed for item number format change. You could run it on your data, but you will lose information that exists in Adagio but not ACCPAC, such as item notes and OE invoice history. If you are using IC 8.0B and not 6.8A or 8.0A, you would also lose item history. But it's worth considering.

You may want to get to know an Adagio consultant in your area. They could help you decide on a plan.