I don't have the details but here is an example of factors you might want to consider.
Let's say that you have 6400 sq ft of roof and pavement draining into that sump, and in a bad rainstorm that you want to design for, you have 1.5" per hour. So you have 800 cubic feet of water per hour. That is 6000 gallons per hour, or 100 gallons per minute. You do the numbers, based on your drainage areas, and recent rains in northern California or on the rainfall chart at the site below.
Then you figure out how much lift you are going to need with that pump, and how big a discharge pipe you will need. How much elevation difference + pressure losses + margin of safety for pressure loss. Maybe use 15 ft of head at 100 GPM. So in that case you would want a pump that handles 100 GPM at 15 ft of head, plus whatever flow and head margin makes you comfortable.
At 100 GPM a 2" discharge pipe is probably a little small for a low-head sump pump. Figure 3" or use some of your 4" pipe.
You are running direct rainfall runoff into this sump. Is there any chance that it will flow back into your house when the electricity fails? Water might run the wrong way if the sump overflows.
You are going to need some kind of pressure connection to that pump. Not much pressure but it won't be a gravity drain. And you need some place to put the water where it won't cause erosion. Maybe some nice rocks for a runout.