I have a 16 year old nephew with mustang on his brain. We found a 1968 coupe that looks good for him. The only concern I have is it is originally a 6 cylinder car that the guy put a 289 in. He did nothing else to the car besides put the engine in. What should be my worries when looking at this car. It has 4 lug wheels and the original 3 speed manual trans. It supposedly in good running condition. What would need to be done to make this a safe reliable 289 car? Will the rearend hold up? Brakes? Suspension? Looks like it has the small radiator too. Can I make the changes to upgrade it for the 289 over time? Anything that should be addressed immediatly? Thanks for you advice