Magnum Swap with Carb
You need to use the 5.9 Magnum flex plate as you planned, but you will have to open up 1 hole in the flex plate to bolt to your existing converter. If you take the flex plate off the magnum motor, and bolt it to the converter in the truck, 3 bolts will line right up. You will then see what little bit needs to be hogged out of that 4th hole. Others may disagree, but I kinda think a 750 cfm carb is too big for a 360. Sounds like a good swap, so good luck.