The car might be free, but the hobby of racing sure isn't. And if that will interfere with the goal of buying a house then don't do it. How will you get the race car to the track? Need to buy a trailer and a truck. The car has no motor so that's needed as well. And after the first race, you know Tim will take the car apart and it will sit for 999 years!
If buying a house isn't that big of a priority then go ahead with a race car, but having 2 different race cars for 2 different types of racing doesn't make much sense either. Sell the 76 to fund the dirt track car.