Any gotchas when converting a non-inventory item to an inventory one? What happens to the historical transactions that contain them? And to the open transactions as of conversion date?

All existing transactions have the item listed as non inventory unless you edit and re add the item back on. No existing/historical transactions are changed unless you do it manually So if your item number is 12345 It will show on transactions as 12345 (Non Inventory) and for that specific transaction it's treated as a non inventory item But for all future transactions it will be Inventory

Got it. Thanks!