How did you pick your torque converter?

You can not use a neutral balance converter (no weights) with magnum engine unless it has been internally balanced.You will need a flex plate to make up the difference. Get intouch with John Cope,he can give you the lowdown on what is needed.
https://www.coperacingtrans.com/contact_us.php?osCsid=a1ac547edfec1b25f24403b7772819c7