I can't speak about kubota tractors but I have run Kubota motors in my skid steers since 2002. I have had everything from 46-92 hp in kubota and just about everything in-between. If the rest of the machine is built as reliable as the motors, then I think you would be okay. My father in law has an old B3000 or very close. Many years of service and solid machine but no FEL on it.
"Life is tough, but it's tougher if you're stupid."