Help needed! I have a '68 cuda 340 6 bbl. , headers,mild cam,etc. Went to run it,it cranked and died.Changed fuel filters at elec.(Holley) pump and at regulator. Cranks but won't run. Thought mech.pump might be bad,ordered one and replaced it. Still won't run. Checked spark @ no. 1 cyl.;have...