we have an old 5000 for its got roughly 16000hrs on it and we just redid the lower end and pistons as well as the rings.. they are tough old tractors as ours has been used hard and still cranks and runs good
I've been looking up some stuff about oil bath filters lately, turns out my old '71 Opel Rekord C uses it too! I read it is way more effective than paper filters (that's why it was mainly used on big trucks and tractors)
You can replace the oil bath with the paper filters, but it won't work as well, people do it alot with VWs & regret it either. Just saying good choice on keeping the oil bath that was designed for it!!!!