Congratulations! These are fun cars, and are excellent for autocrossing. Hopefully things will work out so that your son can get to drive it in a performance setting, so he can learn some car control skills.
Welcome!
Hard to go wrong with an $800 boxster! Especially when you are a DIY-er and have AUTO-X as the goal.
You and your son will definitely enjoy that project.
I take it you've already sourced your replacement motor?