I HAVE A 455 OLDS IN MY 64 CHEVY AND IT RUNS GREAT, HARD ON GAS THOUGH. THERE IS A GUY NAMED **** MILLER WHO SPECIALIZES IN OLDS HIGH PERFORMANCE ENGINES. IF YOU WANT TO KNOW MORE CHECK OUT **** MILLER RACING .COM. I HAVEN'T REBUILT MINE YET BUT WHEN I DO I'M GOING TO GET HIS EXPERTISE. GOOD LUCK , IT'S WORTH 300$ IF IT RUNS