Assuming your yard is relatively flat, I'd be looking at the Z700 line or Z930M with 60" mower deck. At the VERY least, you could go with a Z540R with 60" mower deck. Any of those models can handle that size of yard. If playing the long, long game, buy a Z930M with 60" mower deck and suspension seat. I own one myself and only mow 3/4 acre! It's overkill but they will last and last, and cost you less money over the long run. I work at a dealership. Hope this helps!