B&M Flex plate 10241 360 Magnum/904

They are scarce, Mancini had them for $250 a while back. B&M stopped making them
Some yrs ago. If you find them reasonably priced, pls post here. I would like a spare

The 10241 as far as I know is the only one out there for this application that is SFI safety certified.

If you could get by with less,,,
check out ATPz332 at Amazon for $54.98.
I Googled 360 magnum flex plate

I was never able to find a definite, clear answer on the balancing of 360 mag engines

IIRC, my research indicated that up to 1996, the balance was added weights to the flywheel. After 1996, balance was added weights to the torque converter. (Yes I know I'm going to get crap for saying that )

Not trying to rain on your parade, I have seen plenty of mismatched converter/flywheel/balancer situations, some that vibrated so bad it would be rattle your teeth.

Please let us know the results of your situation

The 10241 will work on a 360 Mag to 904, with a NEUTRAL balanced converter.

For added assurance get if possible, get your entire rotating assembly balanced