Remove coating on Dansk Battery Tray?
 

I purchased the Dansk battery support and tray for my 914 from Restoration Design. They have a black coating which RD believes is an e-coat. I consulted with RD and they believe that it is best to remove the e-coat so that the primer etc. will adhere and the finish will look the same as the rest of the car. But, they suggested to consult with a painter. My understanding is that one should only scuff the e-coat with say 400 grit and then epoxy prime etc. But, if it's preferred I can blast the e-coat off and then epoxy prime instead. What is the best way to proceed with these parts?