Welcome to DT.
I have a 4520 and I have a 84" snow push on the front of mine. Its very heavy, but the tractor has no issue with it. I can turn no problem unless I get it loaded full of very wet snow. I run 440 pounds of wheel weights and I do not use a balast box in the winter.
If I had it over again, I would buy a 72" snow push, but I got a helk of a deal on the 84.
I would suggest you run a 72" blade.