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.