Hi Ron, I think that all the larger displacement LT5's, like the 368, 400, 415 and the 441 and 427's which range in hp from 500+ rwhp to past 650 rwhp still use the OEM DIS ignition.
I would hasten to add that I am not fluent in making any of these bigger inch LT5's...it's just that the ignition system is never mentioned as having been supplanted by another system other than the OEM system on these motors.

Tom