Flywheel

You need to make sure the pilot hole in the crank is drilled to the correct size and that it is deep enough for your trans snout.

I would ask your engine builder about the balancing. The flywheel is zeroed on an internal balance and counter-weighted on external balance. Internal is better! It's what you want!~:-D

:dontknow:What flywheel?.....
http://www.ramclutches.com/Products/flywheels.htm
The flywheel is the foundation of the clutch system, and because it is an energy storage device, also determines the amount of power available to launch the car. A heavy flywheel stores more energy as it spins than a light flywheel. If your engine and gearing combination requires more power or inertia to make the car launch without bogging the motor, you will want a heavier flywheel. Keep in mind, though, that a heavier flywheel will be slower to accelerate through the gears. A lighter flywheel creates less inertia at launch, but will accelerate quicker through the gears. In order to effectively use a lighter flywheel, you must consider the car weight, operating RPM of the engine, and most importantly, the gearing. Too little gear will cause the engine to nose over or ‘bog’ on launch.
http://www.summitracing.com/search/Department/Drivetrain/Part-Type/Flywheels/Make/DODGE/?Ns=Rank|Asc