Then I would say to use the Dremel w/a stone to get the majority of it out and then swap to one of the smaller metal tips that will allow you to get into the smaller cracks and places like that. An pneumatic die grinder works well if you have one. You can get come pretty aggressive carbide bits that will eat fast. I just don't know what you have readily available to you.
If you are going back with JB weld make sure you get it back to clean metal and wipe it all down good with acetone. When you put the new stuff on, wet your finger with the acetone and you can smooth the surface of the JB weld after it's on. Makes it look better and you don't have to do has much filing after it cures.