There is very little distortion in Angus's tone, and even less in Malcolm's. That's the first area where people get off the track. I can get really close to their Back In Black era tones with an MBritt '69 Plexi profile, gain fairly low and a boost in front of it (part of Angus's secret sauce is the wireless he uses-including in the studio-that has a hot output that hits the front of his amp pretty hard).
angus also has his guitar on 6 or 7 and rolls to 10 for the solo....