I posted this in the Conversion forum, but here is an LS2 GTO accessory list from my conversion. The F-body LS1 alternator brackets are listed because the GTO alternator is stupid expensive!

Edit: The prices are with a 25% discount, you might be able to get the same from your dealer if they know you'll be buying several parts.

Part -GM # -GM Cost
Fuel rail O-ring kit -89017587 -$28.95
Fuel Rail -12572174
Fuel Injectors(8) -89017586
Fuel Injector Retainer (8) -24503227 -$13.04
MAF -25318411
Starter -92169668 -$280.22
Water Pump -89018034 -$236.33
Power Steering Pump -92161580 -$259.74
Power Steering Reservoir -92176477 -$47.09
Power Steering Bracket -92066673 -$26.60
Power Steering Bkt Bolt -92138830 -$5.76
Power Steering Pulley -92066499 -$45.02
AC Compressor -92175482 -$451.61
Compressor Bracket -92066950 -$48.89
Compressor Bkt Bolts(6) -11515771 -$19.14
Compressor Bkt Bolts(2) -92138526 -$22.70
AC Lower Belt Tensioner -12560345 -$59.83
AC Belt -4K430
Drive Belt -6K785
Pulley, Top Idler -12557335 -$31.73
Drive Belt Tensioner -92111701 -$37.64
Drive Belt Tensioner Bolt -92138257 -$8.50
Drive Belt Idler Pulley -12563326 -$36.68
MAP -16212460 -$62.50
FAST Intake gaskets -30-54009-8 -$31.40 (from FAST)
FAST throttle body gasket -30-54011 -$9.27 (from FAST)
Fuel Rail Cover, right -92066954
Fuel Rail Cover, left -92066955
LS1 F-body Oil Pan set -12558762 -$199.79
Oil Pan pick-up tube -12558251 -$33.91
Oil Dipstick -12551581 -$9.99
Dipstick Tube -12551577 -$7.04
Oil Deflector -12558253 -$17.83
LS1 Alternator bracket -12563327 -$15.66
LS1 Alternator bracket -12556915 -$11.53
Upper Rad. Hose -10271554 -$30.48
Lower Rad. Hose -10271555 -$18.41
Steam Tube -12556452 -$10.55