Josh, check with a local community college and take a couple welding classes. I highly recommend it. Being able to properly weld your own stuff really opens up your project potential.
Personally, if I was building a splitter, I'd stick with 3000psi, but go with a big 28GPM pump on a 5" cylinder and a big enough engine to spin the pump without needing a 2 speed pump. That thing would be a splitting machine! If you can find a cylinder with an oversize rod, that will speed up the return stroke a lot as well. A regenerative valve is another way to speed up cycle times as well. Lower pressure with larger cylinders is going to be cheaper and safer in the long run.
Personally, if I was building a splitter, I'd stick with 3000psi, but go with a big 28GPM pump on a 5" cylinder and a big enough engine to spin the pump without needing a 2 speed pump. That thing would be a splitting machine! If you can find a cylinder with an oversize rod, that will speed up the return stroke a lot as well. A regenerative valve is another way to speed up cycle times as well. Lower pressure with larger cylinders is going to be cheaper and safer in the long run.