Fueling & Injection - Ls1 vs Ls6

I've been having fueling issues and just put a new pump on my 2000 Ls1 Z28 and still problems. Anyways I've got a new fuel rail off a 2003 Ls6 Z06 with pressure regulator and injectors out of the Z06 also. They look the same but does anyone know if the fit / function the same. Just trying some random troubleshooting. Any help would be appreciated.
NOTE: After turning the car off it sat 2-3 hrs and when I hit the schrader valve on the rail it didn't even let out a drop of fuel.
Thanks guys!!!

Fuel rail is the same. Injectors are slightly higher flow. All 01+ had 28.8lb. 2000 should be 26 lb.