Okay, aside from the obvious revamps in AC, such as Those Who Fight and One Winged Angel, I noticed that some of the seemingly new AC tracks contain parts of songs from the original game. I noticed that in the ACC version of The Chase of Highway, the Turks Theme can be heard at 5:23, and part of Crazy Motorcycle Chase can be heard at 2:06. (Listen to 0:35 in Crazy Motorcycle).

Any other short bits I missed?

Well, a few bars of Aeris's Theme appears towards the end of Divinity II (when she seemingly appears to help Cloud through the plasma ball to destroy Bahamut Sin), plus Sign is very similar to Shinra Company in melody, although whether it actually includes the Shinra theme is open to conjecture (the fact it's used during Rufus's meeting with Cloud at Healin would support that). Finally, End Credits naturally is a medley of several themes from the game, including the Main Theme of FFVII, Aeris's Theme, and, fittingly for the end credits, the traditional FF Prologue (or Final Fantasy).

Also, unrelated to FFVII's OST, it's worth noting that the beginning of Beyond the Wasteland is very similar to The Landing from FFVIII.

Other than that, there are probably other tracks that feature various cues to the original game's soundtrack, but those are the only ones I can pick up on.