360 does not seem to be making power and is slow in the 1/8. Need help and/or suggestions

Do you know if the person you sold it to is doing anything with it or not, and where it ended up. I have a son in the same situation, he raced my 2012 Challenger R/T from time he got his licence. In 2018 I let him take the Dart for for a test & tune day, and now the low 13 second Challenger isn't fast enough. So we go back and forth running the 10 second Dart. I just keep remembering what a nice race car that Mirada was when I finish it, it ran 10's with a W2 small block. Wish I had kept it, but I had nowhere to store it when I started putting the Dart together and the now ex wife would not give up her spot in the garage.