Message: This address was exclusively generated for the RBF-challenge <https://bitcointalk.org/index.php?topic=1306983.msg63398077#msg63398077> and I have the private key of this address. citb0in, 2023-12-27
Address: 1C8uD9G4AGQas5sG15869p5B1mrF3RELY3
Signature: IAMmKuX5C2Z97eCSjYjfAN49hApXTk2LcMLzHWUp/vYYTxmKsHGaUdc7KQRFilTHUyqiEGt0B3NFqanjcgWl/Fg=
Pubkey can be calculated with the information you provide and it takes a few seconds to find the private key. Because you said it was in the 66 bit range. I think you should not send coins to this wallet.