A 64-year-old man with a history of heavy alcohol use presents with abdominal distension and lower extremity oedema. Examination reveals jaundice, ascites with shifting dullness, spider angiomas, and palmar erythema. Laboratory tests show albumin 2.6 g/dL, total bilirubin 3.0 mg/dL, INR 1.7, and mild thrombocytopenia. Which scoring system is most appropriate to estimate his short-term mortality and guide timing of liver transplantation referral?