[68 C-10 KID]

Late to the conversation but ill try to help.

1.Start with fuel level. On the Demons they like fuel 3/4 way up sight glass adjust the air fuel screws 1-1/4 turns out. slowly bring them in to get the best idle quality 3/4-7/8 turn i bet. make sure jetting is stock, check power valve size against engine vacuum.
2. make sure front and rear discharge nozzles are squirting fuel
3. flow your fuel pump and check PSI 6.5-7 to make sure you don't have a clog, you will need to make sure you have correct fuel line size from pick up to regulator.
4.35-36* of timing is all you should need
5.check spark plug gap .035-.040 peding on compression.
6. ohm spark plug wires or replace with new