A GM or Chrysler power steering pump (both are Saginaw) with a remote reservoir will do the job. It should cost a bunch less than $165 at the local auto salvage yard, and even less if you know someone who is in the process of scrapping a GM or Chrysler car or truck. Pump flow is about 2 gpm for cars and light trucks, about 4 gpm for heavy duty trucks with hydraulic assist for brakes and/or clutch. Relief pressure is in the range of 1250-1450 psi.
Reservoir capacity should be at least 1 gallon or 5 times the cylinder volume, which ever is greater.
I've got a Pequea 5,000 pound single axle dump. My pump is close to $500 and has a 2 gallon reservoir. We used to make small car lifts that would raise the front end high enough to change the oil or tires. used one bull dozer ram and a power steering pump it a little electric motor. Worked well. My friends dad was a heavy equipment mechanic and he had two little lifts for cracking tractors in half for clutches and such. One end was on some kind of trolly so he could roll the front half of the tractor forward. Ratz, old thread. Wonder if it got fixed?
I've built a couple tilt trailers and dump trucks and found the electric/hydraulic pumps are the easiest to use. I buy 2ga 20' jumper cables for around $25.00 at the local farm store when they have them on sale. Take the clamps off both ends and put a terminal on 1 end to connect to the battery and then run the cable along the truck frame to the rear. At the rear I get a quick connect on the cable ends so I can just connect the Pump when needed. Also have a set of jumper cables made up I can plug in so I can jump someone when there battery is dead.
My buddy just wrecked his dump trailer. He actually had a 5 horse or so gas engine with direct drive pump (think log splitter). Trailer was overloaded with rocks or sand, and the hydraulic cylinder’s rod turned into a banana. Needed too much other work to be worth fixing. The gas engine was a nice solution to a dead battery for an electric pump. It was used too much for the battery to recharge between cycles.