Balancing a Scat cast crank

Hi Valkman, I 'm into a similar situation as you was. How did this end?. What options/path did you choose and what was the outcome ? Reason for asking is that I have an internal balanced 408 stroker setup and I have unbalance in the engine/gear. My manchine shop advice me to arrange for external balance of the damper and the converter. Could it be that the the SCAT crank and the .Chrysler Rod 6.123 is a bad design? (means difficult to balance?)

Engine ....................................................Small Block Mopar 408 inches stroker.
Dyno Numbers .......................................452HP at 5500 RPM , Torque 308 lbft at 3000 RPM, 473 lbft at 4400 RPM
Cylinder Heads .......................................Pro Comp CNC Heads
Bore & Stroke ........................................4.000
Comp .....................................................10.5:1
Intake .....................................................Mopar M1 Single Plane
Crank .....................................................Scat crank, Stroke 4.000
Piston .....................................................Forget
Rocker Arms...........................................Procomp Electronics, PCE261.1085. Rocker Arm Ratio: 1.60, full roller, stainless steel.
Crankshaft..............................................Scat stroker crank
Camshaft ................................................ ISKY, .525 lift – duration 232, tappet lift at 050 on 112
Balanced ................................................Internal balanced, balanced assembly
Connection Rods ....................................Chrysler Rod 6.123