360 magnum /a833 trans question

Use a 318/early 340 flywheel that is neutral balanced.
The number you listed is for an external balance stock 5.9 Magnum. Do not use that one.
I cannot give you a known good number since my catalog does not list one for the early LAs. I could guess at the following;
P4529142 NOT SFI, for 30#, and
P4876047 no descriptor,for 18.5#
both are 130tooth, 6-bolt, and steel.
Neither say anything about balance.