Regardless of the form that is referenced, here is the citation on what is part of the cost basis. Basically, if it related to the mortgage, it is not part of cost basis, it is simply a persnal expense. Look at fees and closing costs on page 8.
https://www.irs.gov/pub/irs-pdf/p523.pdf
You received a document when you closed on your home that reconciled all the ins and outs to determine how much cash you needed to close. THAT is the document that supports what you spent you cash on.
this is a government website that discusses the document.
https://www.consumerfinance.gov/ask-cfpb/what-is-a-hud-1-settlement-statement-en-178/
https://www.consumerfinance.gov/policy-compliance/know-you-owe-mortgages/new-disclosures-streamline-...
