Worked for me!!!
The only thing that he should do is respray some more epoxy over any filler for proper protection. You will go to either the original paint or bare metal when the filler is sanded and feathered in. SPI recommends overnight cure - and from my experience, it is necessary as it will stay thumb nail soft for 4-8 hours or more.
I used SPI epoxy, then in some areas some spray polyester or 2K if I needed some minor fill then finished with DuPont Chromabase BC then SPI Universal CC. For the most part, the topcoats were over the epoxy