No crank or start

[Swagfu]

Go back and verify the plug wires are in the correct position. This happened to me and I had two wire switched around. Fixed them and the truck started right up.

 

[Doubeleive]

Go back and verify the plug wires are in the correct position. This happened to me and I had two wire switched around. Fixed them and the truck started right up.

that would probably matter if it tried to start in park

 

[exp500]

You definately need Frame to Body and Frame to engine grounds, Along with another 10 Ga to Radiator support from battery. Your no headlights should have lit the way for you.

 

[Hoesgottaeat2]

X2 with what @east302 said in post 10. If it cranks in neutral but not in park, I'd be looking at the switch too...

 

[rockola1971]

First you gotta get those grounds corrected. Check starter relay terminal a7 in the schematics on first page here and see if ground is connected to the coil of starter relay. It will never crank without bypassing the relay if that ground is missing.
As far as your ignition problem that distributor has to be set dead close to "Zero" point and then adjusted with a scanner while engine is running(this is because the engine has electornic ignition advance). There is also a plug you have to disconnect during the procedure.
How do I know you ask.....I had a 1999 GMC Sierra Z71 Vin R and I sold it with almost 300K on the clock with original engine that has never been opened up and had 82k when i bought the truck.. Its still going today and I sold it over 2yrs ago.
Recheck your firing order on the wires at the cap. Get it to TDC#1 and see where the rotor is pointing.