I got bored and drummed up some pics of what a 72' inch rear rake looks like on a glorified lawnmower
I think that's the same size rake jwasbury posted on his real tractor (maybe his is an 84?). With a rake you can go darn wide. With rear blades and boxes on a SCUT/CUT/full size tractor (whatever you end up with) don't go too wide, just enough to clear your rear track width. narrower is better.
And here's a pic of a rear scoop on someone else's 728- I'm not pushing the 728 by any means (infact there are some good reasons not to get it), but I think it's cool what such a small gardentractor can get away with:
Also think in terms of snow removal if applicable, you will want a good front blade for that driveway. Here's a self gratuitous pic of a snow blower I restored, but unless you get a lot of snow, most tractor forum guys say that once the novelty of the snowblower wears off, the blade is what they use the most. I have found that to be true.
Also, that Kubota you posted a pic of in your original post has a fairly high center of balance. If you are on an incline like I am, consider getting wheel spacers to widen your track. I filled my tires with antifreeze and got wheel weights and put 1 inch spacers on the rear. Looks *****en and really stabilizes the tractor.