To emphasize what Otto said, that pump is probably too much for your truck. Browsing through the Spectra catalog,
THIS PUMP would be more suitable for your application. The only problem is that it's a 12V pump. I didn't find a suitable 6V pump in their lineup.
Additionally, for safety, any electric pump should have a shutoff relay to kill power to the pump when the engine is not running, with an override from the start circuit. That keeps the pump from dumping gasoline in the instance where the engine stalls for whatever reason, including a feed line brake that starves the engine of fuel - which might then be dumping on a hot exhaust manifold.
Spectra 8108
Average Flow Rating: 41 gph (THIS MAKES NO SENSE BASED ON THE FOLLOWING INFO)
Maximum Flow Rating: 28 gph (THIS CORRESPONDS WITH NOTHING IN THE WAY ON THE OUTLET - AS IN DISCONNECTED FUEL LINE)
Maximum Pressure: 6.4 PSI (THIS WOULD CORRESPOND WITH A NO-FLOW SITUATION - ASSUMING THE NEEDLE VALVE IN THE CARB CAN HOLD THAT MUCH PRESSURE)
Minimum Flow Rating: 18 gph (THIS RATING WOULD BE THE MINIMUM YOU EVER NEED - SHUTTING OFF THE FLOW FOR AN EXTENDED PERIOD WOULD TEND TO DAMAGE THE PUMP)
Minimum Pressure: 3.9 PSI (THIS IS HOW MUCH PRESSURE IS AVAILABLE AT THE OUTLET OF THE PUMP WITH NOTHING CONNECTED.)
In order to use that pump, you should install a pressure relief valve with the outlet directed back to the tank. This is different than a pressure regulator valve which controls pressure on the outlet of the valve, driving the pump outlet pressure up. A relief valve controls the pressure at the outlet of the pump by bypassing flow to a low pressure point (the tank). That would bring the delivery pressure within the spec that Otto posted for your carburetor.
