bypass the ign resistor to start with, see if that makes for a fatter spark at the plugs - get a proper 6v coil, the 12v one may have internal resistance - check the dist cap and rotor, clean the points
take a battery cable off and put a VOM meter between the batt post and cable and see if there's some current flow with truck not running [or a 6v bulb if you've no meter] - that'll show if some of the hash wiring is causing the drain that runs the battery down
Bill