I practice in Philadelphia. The loan interest may be greater than the interest on the late filing, but you just have to be aware of that. It is correct that you may need to escrow funds at the closing to pay the inheritance tax - most likely if the return is filed after the sale you would just inform the escrow company that the return is being sent and the escrow will generate a check straight to the Register of Wills or Dept. of Rev. (there is a "lien" but basically the escrow of funds would handle that). I would always recommend an attorney assist you with the sale of real estate as it is usually one of the largest financial transactions anyone makes.
This is not legal advice nor intended to create an attorney-client relationship. The information provided here is informational in nature only. This attorney may not be licensed in the jurisdiction which you have a question about so the answer could be only general in nature. Visit Steve Zelinger's website: http://www.stevenzelinger.com/
You can likely wait until settlement to pay the tax. You could obtain a loan if you want but the interest charged by the state is going to be pretty reasonable. You can find out the current interest from the Register of Wills, which should be goo through the end of 2013. You should have an attorney help you with the petition for probate and the administration of the estate.
Once you have opened the estate, you can hire a realtor to help you sell the house. The house can be sold even with unpaid taxes - they can be paid at settlement, or money can be placed in escrow for payment of the taxes. But there is no reason to sit on the estate's asset any longer. Make sure the property taxes are paid and that you maintain insurance on the house until it is sold.
Legal disclaimer: The comments above by Dale Larrimore, Esq. are provided as general information and not as a legal opinion or legal advice, because all facts are not available. The person requesting information and all others reading the answer should retain an attorney in your state who can examine the complete facts and provide a legal opinion on your case. All information provided in the above answer and other information provided by Dale Larrimore, Esq., of Larrimore & Farnish, LLP, does not create an attorney/client relationship within any state or under Federal law.