Could anyone steer me in the right direction to buy/modify a manual trans flywheel for a cast crank 440?

I've searched various sites for info and seem to find only vague reference to what's really needed.

So this is a 1977 440 from a motorhome and has the correct external balance dampener and I'm putting an A-833 trans behind it.

I understand I'll need to drill the crank for the pilot bushing plus get the proper external balance flywheel.

But I'm not finding a ready to go flywheel on the various auto parts sellers.

From what I've read I could possibly:

1) Buy a neutral balance flywheel and add the proper bolt on weight (But haven't found a flywheel with threaded holes for the weight)
2) Find the instructions for drilling a neutral balance flywheel per the Mopar Performance Chassis manual (can't find the manual)

Help!