A general note on recording residential purchases and sales contracts is that they should comply with your state's statute of frauds requirements.

I don't know where Micheal came up with the MLS connection but even if you could get a list of NODs from the MLS there is nothing illegal about that either, your not a member and thus not subject to their rules which are not legal statutes.

Michael, I think you are referring to "the statute of frauds".

@Chris SeveneyIs the maturity date the same as statute of limitations?

Not only is that a true statement, but the statutes and law that PA has for this is all over the place; there is not just one place in the statutes where you can go looking and find everything real estate related.

Every state has statutes of limitations on how long a liability may be in effect before you lose the right to enforce it.

The landlord tenant code is generally a state law statute. 

If there was a will then it will control who gets the house, otherwise the relevant state statute for intestate succession controls inheritance of real property, but probate will likely be required to get clear title.One strategy might be to obtain Quit Claim Deeds from the heir(s) and rent the property while waiting out the IRS lien. 

Some of the files are somewhat stale, but still within the statute of limitations for our state.

I've been through this prove it stuff before, you can begin by reading collection requirements of secured indebtedness in state stautes and then go to federal statutes, Fair Collection Practices, & the UCC.The idea is that over time a creditor abandons the claim if they fail to make an active effort to collect a debt.