Nothing I had read before said anything about different flywheels for the factory turbo. I never really thought about it until your 1st. post in this thread, but it makes sense.
Now, how much difference it makes is a good question. I've read of people interchanging 6.9 & 7.3 flywheels with no problem, & I'd have to think that the difference in piston assy. weight is greater there than the difference between the 7.3 NA vs. Turbo.
The O'Reilly links are disapointing. Based on the engine code, they claim that both flywheels fit IDI's and Strokes... You might contact Sachs directly, with their part numbers. You might get better info there.

Good luck man!
Phy