Ski, you don't need a cycle stop valve - what you need is a VFD controller and motor. No reason to replace the pump end as long as it is still operating with-in the performance curve. -OR- You are going to have to hill-billy the section wiring by identifying total gpm per zones that are similar then slave those to the controller to operate near the rated capacity of the pump. -OR- Place a rather large pressure relief valve on the mainline adjacent to the water edge to dump the excess volume back into the water source. Any way you look at the pump being set up for the "all or nothing start" to use your phrase, volume differential per section is going to seriously shorten the pump and motor usable life unless you do something to address the discrepancies. The good thing about the VFD controllers are they have come way down in price. However, I have no idea what a 10hp controller and motor would cost but since you are stuck with correctly repairing what those hacks installed - you are stuck with a real maintenance headache unless you do something. Personally, the hill-billy set-up is the absolute last thing I would suggest. Price out the VFD controller and motor as well as the new pressure relief valve making sure the operating threshold is correct for your application (remember not all PRV's fit all applications) and inform the client accordingly. The good thing with the VFD is you usually will not require a PRV as long as the VFD is programmed for all 177 sections. Regarding the PRV, if you go this route, make sure you have one that has: 1 - sufficient volume to handle excessive water when the smaller capacity section(s) operate (meaning the overflow discharge is at least three inches otherwise you'll have sharp pressure spikes causing shortened pipe/system components); 2 - has the ability to regulate the pressure without "fluttering" which is what happens when a pressure valve has the set-valve opened essentially all the way particularly when the PRV has the wrong operating pressure threshold.