Hi built this one for my dad years ago. Primary re-purposed scrap iron from metal recycler. So, you can build reasonable affordable splitter. The fender and tongue I bought new steel. I got the axles from a wrecking yard. I chopped the axles off with a chop saw and build good heavy axle. The tank I made also... designed it to disburse the oil inside the tank with a spray pattern on the return to help with the cooling. The thing to remember with high-capacity pump is the heat! The bigger the tank the better, and I use automatic trans fluid. 2 stage pumps are the way to go if you're down on horsepower, but flow and horsepower aren't going to make up for cylinder size that's what limits what the slitter will do. Also, remember wood has grain and the ram is going have side load so remember to brace the slide, so it doesn't bend the guides. With a really fast splitter you may not have time to back off on gnarly piece before it wrecks something. I'd size the pump to the horsepower of the motor you have. Another thought... is buy a used rider lawn mower with a rusted-out deck and reuse the motor. If size of the splitter is the issue, I would use the vertical shaft plus they are usually cheaper more available. If money not object and you're buying a motor i would go with the horizonal shaft, it just makes it easier to work on the coupler & plumbing. I would suggest buying sprockets and use a double chain for the coupler instead of love-joy and there's is a different between a love joy for an electric motor vs a gas motor. The electric coupler wears out faster. So, the pump pressure and cylinder size rates what the splitter will do... so it all about surface area and pressure. Most splitter use a smaller pressure pump but there are higher pressure pumps available and rating on the cylinder is a factor as well. This one work well for us, but I wish I'd made it with Mutiple splitter, we never use it vertically. The splitter hangs off the end so just pull ahead when the pile gets too big. Lots of designs out there ...better than this one but at the time I thought this design would do the job. Dads on the fourth motor so it processed a lot of wood. Also, I wished I built in a table that folds up so to keep those piece that need multiple splitting up on the splitter. Picking a big piece wood up again is never fun as you get older. I'm sure whatever you build will be fine but build it as heavy as you can afford. Nothing more disappointing than to go thru all that trouble and have it break or bend. Most importantly design some safety with bypass on pressure... if it ever over pressure and exceeds the rating on the component... it could kill you. I know someone that bypassed the safety on a punch press... it over pressure, the hose broke and when thru his chest into his heart and killed him. You want your system to bypass that pressure and keep it in safety limit to the rating it was designed for... faster and higher splitting pressure are always the best. You're the designer... make sure you understand the limits. Oh... good long tongue is nice when you have to back up...my 2 cents... horizonal motor.