That would be taxed at your regular income tax rate for both state and federal. You don't have to pay fica though.
Since you're in NJ, I'd set $60,000 aside for taxes.
See if you can postpone closing until after you've owned the property for a year. That would lower your federal liability to long term capital gains, which I think is 15% over a certain amount and 0% below that amount. If you have to ask the intersweb you'd better hire an accountant.