it depends the 1965 because its a little older and its the first year the mustang was sold (not including the 64.5). but the 390 is more powerful. but thats not why you buy a classic mustang. they are not very fast they just look sporty. if you are going for looks, speed, and a classic buy a 1969 mustang fastback. any kind in my mind fastbacks are so much nicer looking. but in the end its what you are going to use the car for. so if its shows get the 65 but if you just want to drive 68