I almost had a bad experience with replacing mine as the tank for the new toilet set back just a tad farther than the original. I had a VERY tight fit against the wall with the new toilet tank..Be sure you will have enough room for that
Also, if you are getting the wax seal from a major store you might want to get a seal of both different thickness..(There are two basic thickness of wax seals) That way you are sure to have the correct one and can just take the unused one back for refund..They are inexpensive. I say this because once you get to the wax seal in your old toilet it is sometimes impossible to tell how thick it was originally..JMHO