I think the answer is yes. I tested this at some point... used a 30p timeline. Brought in a 23.976 file that was shot in the 80% slow-mo function (which would, presumably, be 23.976). Imported an externally-recorded sound file. It was like a two-and-a-half-minute clip.
The video clip had slate marks at the start and the finish. I put the 23.976 footage file on the 30p timeline and played it at 125% speed.
Then I lined up the sync marks at the beginning to get them frame accurate. Then jumped to the end, and yep -- the sync marks were accurate.
Here's what I didn't test though -- whether each and every frame was distinct like it should be, or if there was any manner of frame-blending going on. So you'll have to test that part yourself (just shoot some 80% slow-mo stuff, bring it into a 30p timeline and play it at 125% speed). If it looks good and solid, then the answer should be an unqualified YES.
