Automatic to manual swap

The larger one is similar to what some of call a "jeep style" and it fits the converter bore. That is the route you want BUT BUT BUT check that the pilot hole is DEEP enough. You don't need to "precision" drill it (deeper) if you are using the big bore bushing. Just pick a drill that is larger than the pilot to clearance it, and smaller than the bore, and carefully drill it down. Check your measurements.

If it's bored at all, "feel lucky." My 01 5.9 Magnum is not drilled at all!!!!