One of the constants in Nuno's tone regardless of what amp he is playing is his RAT overdrive pedal, the original one with the LM308 chip. You see all kinds of amps he used from 2203's to the newer DSL and TSL n tours and the one thing that always turns up in the pics is the RAT. I thought the tone he got with his Randall amp was killer on the 2009 tour. Oh yeah a Rat circuit in front of that amp too. A Bill Lawrence XL500 will help too but a Duncan custom or JB will do in a pinch.
I picked one up on a whim to try it, while I can't shred like Nuno it does provide his tone, just saying before you go chasing down a new amp try the pedal into you Friedman marshall set to 2203 amounts of gain then run the Rat in front. I bet you will be smiling.
When I want my Nuno tone fix I break out my whiteface Rat reissue!
Nuno Rat pedal setting are

oclock settings) distortion 8:30 am Filter 12 noon Volume 3 pm

There are pics on the net showing what his settings are if you look.