To the original poster, I think a 72" cutter of any type it too big for a 29 PTO HP tractor. A 6' cutter is wider, longer, and heavier than a comparable duty 5' model. A 5' is all you will be able to utilize in all but the thinnest grass. Save yourself some money and grief and consider a heavy 5' model.
I agree with GeneP. A 6 ft cutter in this material may be a bit much for your tractor. I think you might be more satisfied with a 5 ft. Depending on your plans, you might want to consider buying a good used name brand cutter for the clean up. When you have the land like you want it, sell the cutter and get you a nice new one to keep the land clean. You can really bang up a cutter cleaning up....even when you are taking it easy. Mine caught a stump I didn't see and it pealed the side back on it before I could get stopped. You can also save abuse to your tractor by backing into the really rough stuff. Slip clutch or shear pin are a must.