Watch the Angus Young online guitar lesson by Jeff McErlain from Kings of Tone
The best Angus Young in a box pedal I have found is the Box of Rock by Zvex. In fact this pedal was designed to sound like a cranked JTM45 and I believe Mr. Vex has hit it out of the park on this one. It is my main OD pedal and I never go to a gig without it. There are many ways to get at this tone but keep in mind that Angus doesn't use a lot of gain. So set your pedal accordingly, also look for a pedal that cleans up as you lower your volume knob. To me this is essential in any dirt box.