A factory mechanical fuel pump is completely adequate for a rear mounted tank. The gas gauge sending unit needs to match the gauge. If you go with Dolphin gauges just buy the compatible sending unit. I have seen other threads discussing options to run the stock gauge with a aftermarket sender, but requires an understanding of electronics.

Before investing in Dolphin gauges however you may want to do search for user opinions. I've read about several unhappy customers. Here's one I could find easily:

http://67-72chevytrucks.com/vboard/showthread.php?t=312195&highlight=dolphin


1960 GMC 1/2-Ton Pickup Truck
In the Gallery
Updates in the DITY Gallery
Now cruising in the Passing Lane