Motor flattens out at 5k
Do you have the matching springs for the Lunati cam or just the springs that came on the Dart heads? You might be having valve float. Also check your timing adjust the initial to about 16*-18* at idle and rev it to 3000 rpms and hold it adjust the total to 36*. Have you changed springs in the distributor for the mechanical advance? If not use 1 light spring and 1 medium spring, this let the mechanical advance come in sooner. Does this MSD distributor with vacuum advance have a part#? I hope it ain't the cheap StreetFire 8362!