first off, you will probably lose power with the LS1 intake, an LS6 would be a better choice if you did it.
Second, assuming your using truck accessories, you would have to cut off the corner of the alternator/power steering bracket so the TB would clear it and relocate the idler pulley that used to be there. You can use the same fuel rail, the crossover tube will just sit 3-4 inches above the intake instead of right on top of it. For the injectors all you need to do is remove the plastic pintle caps and use a different sized o-ring on them.
I speak from experience, i used both LS6 and fast90 intakes on my truck 408 that i had. Search on performancetrucks.net, there is a decent write-up floating around.
2000 WS6, H/C/I 6.0
470/430 on motor