Jay, I did that swap a few years ago with a complete transmission. Before I installed it, I completely rebuilt the transmission. Somewhere in the rebuild I made a mistake, which caused me to have it professionally rebuilt. After that, there were no issues with it, but I had a slightly different sort of 3.0L.

The main advantage of the lockup torque converter is better fuel mileage, but it might be at the expense of a smooth power curve through the gears on acceleration. Where the non-lockup torque converter allows the engine to maintain revs during the shift process to build momentum in the next gear, the lockup converter eliminates that and clamps down at the shift. I sensed that a naturally aspirated 3.0L might have a flat spot as soon as the shift occurred - mainly because my engine often went into boost at the shift to main power demand from the throttle setting.

It's entirely possible that the Diamante cams I was using also contributed to the issue for me. The truck cams may work just fine with the lockup converter, since there is more low rpm torque with those than what I installed.