If it helps anyone, I had made a quick recording of a stock Epi Silverburst during a brief encounter. This should give you some idea of the tone with those geetar humbuckers. The sound can be serviceable at times, but it is definitely not in keeping with that characteristic ballsy "Thunderbird sound"
For this test, I had cancelled out the bass tracks on a Kraan and Meters recording and played the Epi right over the top. In the Kraan song, I'm using a pick with the neck pickup on full, the bridge pickup rolled off just a bit, and the tone control wide open.
The second half of the clip features fingerstyle playing over a Meters song. Here, I'm using the bridge pickup only with the tone rolled off all the way.