I was thinking of putting '57 Classics in my G400 but I was also thinking 490 Alnico magnet humbuckers...
Desperate Times, Desperate Measures.
or Neck Pickups: 490R Alnico magnet humbucker Bridge Pickups: 498T Alnico magnet humbucker
Desperate Times, Desperate Measures.
Azn_guitarist speaks truth. Listen to him, he has his head screwn on tightly.
The pickups won't make too much of a difference through a crappy amp, sorry!
"Breathe, breathe in the air
Don't be afraid to care"

Fender Strat/Tokai LS80>few pedals>Orange Rocker 30
I have to agree with everyone else. Get a new amp first. The are great for classic rock. I have them in my Les Paul. In my SG I opted for the SH4 and SH2N pickups by Seymour Duncan. The seem to be a little better suited for a wider range of styles. The 57's can be a little muddy.