Goulds is another submersible pump brand worth considering.
It is impressive you are able to get decent flow rate within 100-150'. My experience has been at least 10x for half your projected volume. What do you expect in terms of quality and TDS with your water?
Here are a few pointers I have picked up along the way -
a) the pump size is typically 2" less than the borewell diameter, lesser in the case of using a liner etc. Realistically with a 6" borewell without a liner the maximum pump diameter is going to be 4".
b) given an option go with a larger diameter PVC/steel outlet to minimize friction loss
c) it is typical to size the pump based on 50% flow rate to ensure well longevity. This said it is a nice to have option to install a slightly upsized electric cable, this provides a cost effective scenario if you realize the well generates more than the initial GPM assessment. If this were a scenario, at least the electric wire cost can be reused with an upsized pump at a later date.
d) you probably already have an idea with your electrical source power settings - single or three phase for desired pump selection
From your messages, it looks like you plan to store water before trying to run the irrigation sprinklers. In this scenario your submersible pump/motor just needs to be sized for the distance from the pumpset level to the storage tank inlet height. The one other component necessary with your submersible pump is the control - using symcom/littelfuse motor saver is a common option.
What is the elevation difference between your well site vs storage tanks vs highest and farthest watering sections on your site?
As for internet vendors I would recommend calling the corporate offices of your desired pump brand, and asking for their respective regional authorized dealers. These dealers will also help with the correct sizing and necessary details. The other option is to check with your driller.
Once you have the submersible equipment sized, you have one more project sizing up the booster pump side for stored water distribution.