My 70 won't start

[Dads 70 long bed]

My 70 C10 wont start.
new plugs, cap, rotor, wires, coil, points and condenser.
I put her in the garage to rebuild the carburetor.
Now, no spark. the points are at .030, the positive side of the coil reads 5.7 vdc
the negative side is zero. The run terminal on the starter solenoid reads 5.8 vdc I use the black side of my jumper cables to reference ground and clamp it to a spark plug to look for spark. I can lay the plug on the cowl to watch for spark, since I have no help.
Any ideas?