You can’t know where an eventual buyer will come from from the overwhelming majority will be looking on the mls.

An empty building can be great for a buyer, funding will be a different story however.

In the Schedule B Exceptions from Coverage of the title commitment, it states a "Memorandum of Option" between previous seller and buyer in 2013.

Or, will buyers ignore it as its technically unfinished?

Find an agent who is an investor. go to meetups in your area to get exposed more and network. picking up random properties on Zillow with out knowing all the expenses and repairs isn't the best way to utilize the calculator. you will need accurate numbers to see if you will cash flow. start your search for a property now as sometimes it can take time to find the right one depending the area. get pre approved and go house hunting with a link minded realtor. then you can plug in the numbers into a calculator and see if any will work. best of luck.

You can clear the title by doing a Quiet Title action using an attorney or hunting down the previous owners and getting Quit Claim deeds from them and a release on any old mortgages.

Sellers will give an advantage to pre-approved buyers over other buyers who are just kicking tires.

Do any of you send direct mail pieces  to cash buyers?

I have a referral for a buyer in that area.

There may be ethical reasons to not assign a contract (my personal opinion is that (1) if the contract provides seller financing or other terms that rely on the performance of the buyer after the closing, it is unethical to switch buyers without the seller's permission or (2) if you haven't properly vetted the assignee or used language to prevent them from also assigning to someone who can't perform and you are not able to close if they fail to, that is not fair to the seller) but that is a personal opinion not a legal distinction.I'd be interested in taking assignment of your contract if it is a truly profitable deal.