Technical Tri Five Chevy Last 10" Trunk Repair

Question for those who came before and tackled the last 10" trunk repair. I have to do the same on my 56 and I just received the Real Deal Steel kit they sell as pictured. When holding up the new tail panel to the original still on the car I noticed there seems to be an inner structure where the trunk striker mount welds to the inside of the tail panel and this is not part of the new panel. The top lip of the tail panel folds over this inner structure. Looking online I don't see a new piece that sells anywhere so I am assuming guys just reuse the original structure?

 

I believe I've always used the original part but it's been 12 years since I've done a Chevy.