duster sparks from battery ground

Don't hook up the battery again until you find the draw using a multimeter (ohm setting). I carry a multimeter in every car, all free at Harbor Freight w/ coupon. Anything less than 100 ohm from BATT+ cable to chassis ground should be a concern. If you disconnect your bulkhead connectors first, that will isolate it to the engine bay (alternator diodes, starter, starter relay, horn relay, wiring). If not there, reconnect, pull all under-dash fuses and put them back one at a time to find which circuit is the culprit.