Installed new spider. Now truck want even try to start just turns over. Used starter fld and big backfire thru throttle body. Any suggestions. I think I have the nozzles in the correct cylinders

 

Not to sound like a jerk by "thinking & knowing" the nozzles are in the right places makes the difference between running and a no start. I would retrace your steps and see where you may have went wrong....... Also check for fuel pressure

 

Ya after I reread my post I felt like a dambass...lol
I got into this project after it was torn down. I looked all over for poppet locations to make sure I had it right I could not find anything anywhere. So I found a picture of one in my lines are matching that. I pulled all plugs all plugs were soaked in gasoline and Miss gapped majorly so I put in new plugs gapped correctly Goddard fire and she tried to idle but spit and sputter and then backfired again through the throttle body. I'm not sure about the fuel pressure but a mechanic is going to look at it he's a certified Chevy mechanic and find out. The other thing that I told him it could be will be the timing cuz it has two hundred eighty thousand miles on it.

 

Pull intake back off if you look on the injector body the injectors are labeled by number. Verify the spider is installed with pressure regulator on passenger side. I've had "expert DIY mechanics" drag them in with a no start and find it installed backwards and all poppets every which way but correct.
Check fuel pressure

1 and 2 at front of vehicle.

2,4,6,8 passenger side front to rear

1,3,5,7 drivers side front to back