I replaced the head gasket on a 96 4.3 chevy s10 pu get spark but won't turn over?

Does it 'Back Fire' thru carb or injector? Will it continue to crank til it will kill battery? Try to add can of fuel injector cleaner to gas tank and spray cleaner into carb or injectors while trying to crank ! Let me know, OK?

If non of the above works , as a simlpe fix , you'll need to check fuel lines, timing marks or crossed spark plug wires! Good Luck !