For those of you who are metrically challenged, -60 Celsius is -76...hey, wait a minute. That's not too far above the temps found at the "coldest place on earth," the Vostok station in Antarctica. There, it has hit -129 Fahrenheit. Typically, low temperatures run in that -50 to -70 range, so must be that's where you're headed! Surely someone you'll be accompanying or spending time with has some advice on this matter. But I should think at a minimum you'd be looking at expedition-weight long underwear, a full set of 300-weight fleece (the R3 is equivalent to that), and then a really, really serious down suit as outerwear. Feathered Friends' Down Suit ($800) might be the ticket.
Still, for a midweight insulation layer in exceedingly cold conditions, fleece can actually function better than down. Down doesn't work all that well when worn under another layer because the outer layer causes it to compress, greatly reducing its insulation value. Fleece compresses much less - as anyone who has tried to stuff a big fleece piece into a backpack knows.