davebarnes 21, you do not say how deep is the well; I think that the water table has receded to the extent that the pump cannot "draw" enough water to give a better GPM. As far as I know, there are two ways to improve the GPM under these conditions.
1. Dig the existing well deeper so that the well point(s) tap into the lowered water table.
2. Increase the number of well points so that more water can get to the pump from the existing water table.
I have an idea that you can make a cross connection from the artesian well intake to the intake on the old pump.
However there may be code requirements (there usually are) and a valving system to channel the water to the house or sprinkler system as needed. Hope that this helps.

Thanks

The vac guage reg 24' of neg head recently.

I am not sure what the well depth is during normal conditions.

I guess my main questions are;

How can I know how much GPM to draw without over stressing this dug well? Keeping in mind it will only be used in the summer

What is a proper pump / tank combo to do it with?

7GPM for how many minutes?
If 'X' is the minutes, build a tank at ground level having a capacity of 7gpm x X + 15%

If you are having problems holding up your sprinkler heads, while using popup sprinklers, try using the POPUPHOLDUP. I would definitely recommend using it. Great for sprinkler head holding, holder, however you want to say it. '

The POPUPHOLDUPÂ clips onto the nozzle stems of all major brands of fixed head pop-up sprinklers. The stems stay up even when the water is turned off! ItÂs a system designed to hold up multiple sprinkler nozzles at the same time to make routine maintenance of filters, nozzles and flushing a quick, easy, hands free job. For pictures and directions on how to use the POPUPHOLDUP to hold up sprinklers, Click Here.

Here is a link that might be useful: POPUPHOLDUP

Unless you can increase the water yield of the well or plumb into the 2nd well, you are really limited to pumping no more than the 5 gpm capacity of the existing well, otherwise you will run it dry and start pumping a mix of air and water.

Another option is to install a cistern which you can fill at your well's pumping capacity, then run the sprinklers from the cistern pumping at a higher rate. If you do that, you will need to set the zone timers so they shut off before fully draining the cistern. Then allow time to refill the cistern before moving to the next zone.

Yard irrigation uses much higher quantities of water than typical household use, so the well may have worked fine for a household but just cannot handle irrigation.

Lastly, and maybe simplest, is to use sprinklers with a lower capacity so that you can cover more area but each zone will have to run longer to apply a given amount of water.

You also need to determine how much of the acre you actually need to apply water to and how much water per week to apply to see if the well has the capacity to meet your needs at 5 gpm.