I don't think a B is "required" for your use. As long as you keep the MMM off when using the FEL and ground-breaking/finishing 3pt implements, I am sure you'll be fine. I think once fine grade, you'll be wishing you hade the BX for the longer duration of mowing for "X" years over the few weeks/months of restoration work.
Dig up my past posts and more recent past posts. I just ditched my B7510 (basically the B you are looking at) because it would cut circles where ever I turned. The new BX2660 is absolutely niigh and day fantastic. I just mowed again tonight and am amazed.
The outboard front tire on a B when turning do lean out at the top so that the bottom outer edge cut sod. I have many circles to prove it. I have had genuine turf tires and bar turfs (not R4's) with real rounded edges to help minimize damage, but they didn't help. I think the BX is much better balanced and has more weight on the rear of the tractor (axle) where as the B has a fair more bit of weight up front with the FEL subframe alone. My nes BX2660 will turn circles so tight without even hinting at cutting the sod. I only wished I had bout the BX seven years ago when I originally looked, but I though bigger was better.
The new B's have a suspended deck, which is just like the BX. I had a ground contact type on my B, and that is another reason I traded it off. I got pie plates and an uneven cut. Had I really studied the new B2320, I may have had a harder time deciding to pull the trigger on the BX2660 just because I'd have tried to convince myself I needed the B2320 and that it would be better than my current (then) B7510. After mowing with the new BX2660, there is no way I could convince myself now I could get the same results with a B2320 or B2620. The BX is absolutely fantastic. AND, you'll see you barely give up much loader capacity with a BX, unless you are looking at a large B, and for me, mowing is 85% of my use. Good Luck!