[NOT A TA]

Pick a car you see lots of at the track. That way if you have a problem there's a whole bunch of nice folks willing to help ya out who have trailers stocked with tools and spare parts.

BMWs and Miatas come to mind first since I see the most of them when I go to tracks. If dad flys down and you get out on the track for your first session on Sat and have a problem that requires a part or special tool or something with a 1st gen mustang, 80's G body or other old car you'd be limited by the number of people to go to for help. So the whole weekend might be shot for that car just because you had an off and bent a wheel or something where if you had a car like a Miata or BMW there's a bunch of guys that have a spare wheel they'd let ya borrow.

There's plenty of track ready cars for sale for sale right now you could buy ready to go for less that half of what it would cost you to build a car and you wouldn't spend time building it. A track car should be something you're prepared to walk away from if you wreck it.