Possible fuel pump issue

[NJ C10 Guy]

Last year when I bought my truck it had a 110gph Holley mechanical fuel pump on it. About a month after driving it, the fuel pump went bad, so I bought another of the same (http://www.summitracing.com/parts/hly-12-327-11). Shortly after I spun a rod bearing and pulled the motor.

I bought another used gen 1 sbc 350. I put the Holley fuel pump I had bought on, which has probably around 500 miles on it, give or take. The fuel pump has sat for about 11 months or so while I was working on the truck.

I finally got the motor, trans, etc. all hooked up and I'm getting no fuel to the carb. I poured about 3 more gallons of gas into the tank, which was close to full when I parked it. I unhooked the line between the fuel filter and the pump and made sure there's gas there and it seemed to be under some pressure (after cranking the motor). I removed the pump and pushed the lever, which I could hear a sucking noise coming from the pump when I pushed it in. The spring is super tight though and it was very hard to push. I made sure the pump was against the pushrod when I bolted it in. My fuel lines and tank were all replaced within the last 2 years so they shouldn't be the issue at all.

I tried cranking the motor with the fuel line going to the inlet on the pump and nothing on the outlet, to see if I could get fuel pushing out, and nothing happened.

Is my fuel pump bad? Are there any other things I can do to try and make it work? I really don't want to drop another $100 on a fuel pump. My motor shouldn't be making over 300hp/tq. What size pump do I really need? Please help, I just want to get my truck back on the road.