No offense but alot has changed since then. He said dirt oval karting. The margay is best known for sprint. Right now the offset chassis and tire and wheel combos are way different than a few years ago. The best thing and I think you'll agree is to go to the track ask about who's chassis does best there and who has good support. A chassis may do great around the south but not so great in another part of the country. He could "build" a kart by buying chassis, engine, and all the other parts but it would be a bigger investment and just starting out buying a used kart race ready except fitment to his son would be the best investment in the event he has to sell it because they figured out it's not for them. Buy a used kart, run a season and see how he likes it then upgrade. A freind of mine raced sprint,enduro and dirt oval several years ago helped get us started and when he saw our kart he was amazed at what all had changed. Especially in the wheel/tire combos and treatments.