To pump water to a storage tank, you don't have to choose a pump with flow rate that is equal to the water consumption rate. In your case, how to choose a pump is more depending on how the water is consumes. 3000 gallon water consuming at 50gpm last 1 hour while 1000 gallons at 50gpm last 3.3 hours, not even considering the pump continue refilling the tank. If each irrigation time takes less than 1 hour and allow enough time for the tank to be refilled before the next irrigation started, using a smaller pump can do the job and save much money. Pumping to a storage tank does not need to consider the discharge pressure but to consider a pump working in its most efficiency head.
Tuhorse North America has a Total Dynamic Head (TDH) Calculator that helps to choose a pump. Based on your information provided, I recommend these models.
1) TH4-BF-11 , this is a 3HP pump, it pumps 32gpm in your application. Check it out at
http://www.tuhorse.us/on-sale/3hp-th4-bf-11-230v-1-phase/
2) TH4-VC-10, this is a 2HP pump, it pumps 21gpm,
http://www.tuhorse.us/TH4-VC-10/
3) TH4-A-10 , 1.5HP, pumps 17gpm for your application.
The above calculations are based on using 1.5†PVC pipe. Pump to the 1000 gallon tank 80 feet above the well head with 300ft incline.