Ah, now that I know I can speak legal gibberish, that changes how I can respond.
🙂§1.1001-1(e) shows the gain is based on the actual amount received (assuming the seller's Basis is less than the amount received). See Example #1.
<a rel="nofollow" target="_blank" href="
https://www.law.cornell.edu/cfr/text/26/1.1001-1#e">https://www.law.cornell.edu/cfr/text/26/1.1001-1...>
For the buyer, his Basis is USUALLY the actual amount paid, but that can get a bit wonky, depending on the circumstances. See §1.1015-4.
<a rel="nofollow" target="_blank" href="
https://www.law.cornell.edu/cfr/text/26/1.1015-4">https://www.law.cornell.edu/cfr/text/26/1.1015-4</...>
Does that help? If not, please respond with any followup questions.
