I have done the same and bought some after market indicators and located them as per the bellow pic. There was not much room inside for the bolts but l managed by removing a small amount of plastic with a big drill bit.
I bolted a piece of gal tin sheet across the tail just below the tail light and bent the ends forward. I relocated the number plate as it kept falling off due to being made of rubish tin and flipped the plate light upsidedown.

Still need to remove all the other brackets and cut the tail off.
Also scored another complete unbroken tails for $50, noice.