The disc is about like the 14' Minn-Moline disc I first used that we pulled behind a JD 4010 in loam soils. it made that 80 hp tractor work when we engaged the disc. If you go fairly shallow and do not angle the gangs much you should be able to pull it. That old M670 would pull well but I am thinking that the 5000 was not on this disc much. Our two row choppers made our JD 4010 and 4020 work very hard. Ours were IH choppers not NH. Vermeer balers are not lightweight and power sipping either. If I were you I would go up to at least an 80 hp tractor, I would recommend a little larger eve. Once you get above 50 hp going up to 100 hp costs very little more. Tractors like IH 766 or 966, JD 4020, Ford 7000 or 8000.
You will find the extra weight and power will come in very handy. Better to go a little large than cut yourself short. Myself, if I had 70 acres, I would go straight to 95-100 hp and not have to worry about it. Around my area the IH 966/986 are common haying tractors - mower conditioner, raking, baling. The JDs of that era are nice but a few more dollars. The Fords or Cases (970 or 1070), like the IH, can be had a little more reasonably. The Cases always had a few PTO clutch issues but if you go this big you shouldn't have issues. Balers and silage cutters can be tough on PTOs. A few more horses and heavier drivelines will make for less repairs - do not go too small up front.
In truth, if I had 70 acres, I would go to an IH 2+2 but that is just because I like those tractors. I am trying hard to justify one but have not come up with a good reason yet.
