ON A SMALL BLOCK I WOULD PUT 600 ON IT , YOU CAN TRADE THE FUEL BOWLS FOR DUAL LINE STYLE FOR A BETTER LOOK . O-RING THE BLOCK , IT IS CHEEP INSURANCE . I HAVE RUN CAST IRON HEADS AND ALLUM. HEADS BOTH . ONE THINK TO REMEMBER ON A BLOWER MOTOR IS HEADS ARE NOT AS BIG OF A DEAL , BECAUSE IN A NORMAL ASPRIATED MOTOR YOU ARE DRAWING AIR THRU THE PORT ON A BLOWER YOU ARE FORCING IT THRU . SPEND THE MONEY ON OTHER THINGS YOU NEED FIRST , GOOD IGNITION, CARBS, ,PISTONS,