This is how I interpret your situation. Pumped transfer from a collection point to a discharge point over about 150' of pipe with a slight high point in the discharge piping run. First off, there isn't any reason to go to 3", the head loss for 43 gpm with 150' of 2" PVC is about 6'. If you have your pump curve I would assume it's perfectly capable of handling this. Go to all 2", trench the line in where it is in the yard, go under the sidewalk and penetrate the curb. Use a stainless mesh to cover the end of the pipe and you are done.
I used the 2" for the uphill runs. The 3" running downhill relieved the load on the pump. The biggest reason for the 3" pipe was the flow rate of the outlet grate. I wanted to stop critters and such from getting into the pipe during our long dry periods. A 2" pipe has a very restrictive grate where the 3" grate is very close to the flow of a 2" pipe.
I'm using a Zoeller M63 pump.
![[Linked Image]](https://www.zoellerpumps.com/content/literature/Curves/153854_Curve_63.jpg)
When I get my power upgraded I'll install a pump on the other side of the house to handle downspouts over there and help dewater the soil quicker. When that happens, I'll move the existing pump into that basin and drop a Zoeller M98 in the primary pump basin.
![[Linked Image]](https://www.zoellerpumps.com/content/literature/Curves/009971_Curve_98.jpg)
