Sounds like you came up with a very cool way to combine your hobby and your livelyhood. Well done!
My oldest son is 14 and has been eager to help with the Buick since day one almost 4 years ago. He's come a long way in his knowledge of tools, parts, and how things go together.
My youngest is 11 and he's not as eager to get greasy, but he loves riding in the car, helping me get the drag radials on at the track, and shooting pictures and video whenever he gets the opportunity.
My wife realized that the car wasn't going to go away a year or so ago and has been getting me both Summit and Jim Green's Performance gift cards for birthdays, and Christmas.
She says when it's painted she'll enjoy going on a lot more drives with me.