All factory big block engines with manual transmissions had forged cranks right to the end of big block production. That's why you can't find a factory flywheel.
Your only option is to modify a neutral flywheel or verify the imbalance on a 360 flywheel and adjust if necessary.
There used to be a company that made a thin counterweight plate that you sandwiched between the crank and the flywheel but I don't think it's in production anymore.
Kevin
but trucks used external balance flywheels and the LA360/383/400/ cast crank 440 in trucks/MH had a 435 granny 4 speed so that is the factory flywheel that's needed to use the cast crank 440 in a car with 833 4 speed.
not sure what I am missing but the weighted 727 auto TC behind my cast crank 440 is fine.
I had a couple d200 trucks with a 400/435/d60 combo
