car thats been sitting for a long time

alright, a friend of my dads has a 66 289 stang that hes had since he was 16. it hasnt been started in the past 12 years. he just got new brakes and new paint on it, he also had to get a new floor pan and driver side frame rail welded in. its a really nice car and he just needs to put the interior back in it and new exhaust. he claims that it will start right up and hes thinkin about paying me to put the car back together. do you guys think it will start up and run after i put all new fluids back in it? i have an 89 stang and know nothing about these older cars...thanks for the help

thanks man, yeah i figured id have to change the plugs. he just put a new gas tank in it so were good there. i cant wait to hear this thing crank up. ive known him since 5th grade and have been in love with that car. hes got the same setup that he had in high school on it...huge cam, heads, nice carb. thanks a lot