The Eaton pump is 3.5 gpm, 900 psi used mostly on utilities with a PS cylinder. For me the reservoir on the valve cover is an impediment and prone to leakage due the vibration. If converting from generator to alternator mounting a double pulley gets kinda tough. You will probably find it easier to locate repair parts or another substitute for this pump than the Barnes.
The Barnes pump for utilities with PS cylinder is 6 gpm, 1030 psi. The extra boost is helpful in getting out of slow travel tight spots with a loaded bucket. There are substitute bearings, shaft seal and other minor parts available but the pump is basically a throw-away due to the configuration. Generally non leakers except possible shaft seal leak into the engine gear train that may be undetected before it ruins the pump.
The Barnes pump for Ag tractors with Char-Lynn is 4 gpm, 1050 psi.
Personally I always convert to an alternator and don’t want to deal with a separate reservoir on the valve cover. I changed from an Eaton pump to a Barnes 4 gpm on my 310. It works ok but my PS cylinder came off a 700 Ford and is in excellent condition. The 700 & 900 Ford cylinders are mounted up on the left side of the engine and are not subjected to much of the wear and stress of the front mounted cylinders. I wouldn’t recommend the 4 gpm on a marginal cylinder. I have an excellent Barnes 6 gpm that I will someday install when I get over being so lazy.