VICKERS PRV12-10-K-0-50/

Harvesters are actually one of the named applications for this valve, so you're in the right ballpark. It holds up to 350 bar (5,000 psi) and handles flows up to 300 L/min (80 USgpm), which gives you solid headroom for a demanding mobile circuit. The spool-style construction keeps pressure regulation consistent even when system demands are shifting around, which is exactly the kind of behavior you want when you're dealing with pressure spikes. Working flow rate on this one sits at 45 litres per minute, so just make sure that lines up with what your system is actually pushing through at operating conditions.