valve notches in the pistons? piston to valve clearance is a concern. I have a 383 in my dart that went 11.82 in the quarter with 8.8:1 compression and OOTB eddy heads. I drive the car all over. the little 383 can run hard. you are going to NEED a good converter. talk to frank lupo at dynamic. I have a 4500 stall 9 1/2 converter that is dynomite!