I have been around 3 Predator motors. If you just want it to go to the car show, a small inch motor will be fine. If you want to run with the big dogs 605 would be my small and 655 would be ideal. 1400 hp is the norm with 2 carbs and no power adders. If you wanted to run a procharger I believe low 4 second passes and even high 3.90s are there.But that is big dollar block, rods, crank, transmisson, convertor, and especially the car.We are talking pro stock chassis with fire system.Good luck on your "friends" build. Birdtracker