XA, with 2ft undulations to be resolved I'd think that a full sized grader is required. Is there a big road-building or industrial unit bullding project nearby? If so find the earth-moving foreman and explain your interest in a smallish hire job when his machines aren't comitted...
You just might strike lucky, and even for a few grand it'll save in time and effort over struggling with JCBs for weeks at little less total cost. You're talking a huge job for JCB type equipment, and even if it can shift the volume it will neveer get it flat, as said above. Do it right first time.