On my '79, whoever swapped the engine in originally used an inline pump, so the original tank was used. If you were going to leave it injected, that is a possibility. I would go ahead and get an aftermarket harness and have the PCM programmed to get rid of VATS, and roll. With the connectors being in the heat for 20 years, an new harness is cheap insurance, just from that standpoint. I have used
www.fuelinjectionconnection.com with pretty good results.