I have an area in my backyard that after a hard rain will have 3-5 inches of standing water. Unfortunately it is in a drainage easement that is blocked further upstream so it backs up on my property. My plan was to install 4 flo well drywell kits in a large gravel pit so that the water can collect there and leach off over time. One of the fears I have is that it won’t be enough during sustained heavy rain periods of the year so I was thinking of installing an outdoor sump pump in an overflow pit. The one concern I have is the only area that I can send the water to is about 265’ away with about a 4-5’ upward slope. Is there any sump pump that can discharge that far?
In your scenario I'd probably dig a giant pit, install a deep concrete sump on the hill side of the pit. I'd landscape fabric the pit and then install rock into the pit. The rock pit will fill with the water and dissipate over time. The fabric will prevent the pit clogging with fines.
In the case that the pit can't handle the volume, you set a hi/low electronic float switch and have a sump pump pump, when the hi sensor is hit, uphill to a secondary sump pit. I typically use 1/6HP sump pumps, they are cheap and if you aren't cycling them all the time they last a long time (it is typically the on/off that kills the pump, not the pump time). I'd repeat the secondary sump pit up the hill based on the specs for the sump pumps. I'd rather install 6x$60 sump pumps than have to install some super expensive pump that can do the whole job.
5-6' of vertical isn't bad but the frictional losses over the 250' of pipe are going to be significant. The larger the pipe the less frictional losses. I'd probably go for 2" pvc.
You can certainly get pumps that can do any distance. Gold Rush the series typically dewater their mining cuts which are near rivers and use 8" pumps that are taking water long distances and going up steep inclines. These pumps can cost hundreds of thousands. Water slide parks have huge pumps that are pushing large volumes of water upwards of 40 vertical feet in 12" schedule 40 pvc pipe. The pumps on commercial infrastructure like this are likely outside your price range.
The passive approach of a larger rock pit is going to be the better long term approach.
The static head of 5 feet or so (perhaps 10-15 with the pump underground) is trivial for most sump pumps. The distance is mostly a matter of choosing large enough diameter discharge pipe so the dynamic head (friction when actually pumping) is not excessive.
What happens in winter may be an issue - that's a long line that you're probably not going to want to have drain back every time the pump operates, unless you have a HUGE sump so it makes very little difference to the sump level, but with check valves on it it's going to be a long pipe full of water that probably can't be buried very deeply, certainly not at the discharge-into-ditch end.