What does it do when you turn the key?
Does NOTHING (no cranking) or has a security light come on at the guage cluster,you might have an issue with the VATS security system (basically the little security bit on your ignition key and/or how it's being read by the car).
Also check your relays (starter/fuel).Not sure on an LT1 but they should be under the hood in the fuse box.
If the car is cranking but not starting, check your fuel filter (actually seen them get bad enough where they cause a no start condition).
Check all your engine grounds.
Confirm that you have fuel pressure with a guage. Just because the pump has been replaced,doesn't mean that there isn't a seperate issue keep the fuel from reaching the engine,
Hmmm... Kick it!! Sometimes it works for me... sorry.
Good luck man...just take your time.These problems can be a headache.