[Ozark]

I'm considering purchasing a family member's 1986 Carrera coupe with ~300k miles (odometer broke at 265k). It has been a 20-year daily driver and I just had a PPI by its long time mechanic. The engine's tired with poor leak down and compression numbers (rings) but surprisingly uses little oil and runs and drives well. New brakes, tires. 15" Fuchs. Recent clutch. Prussian Blue, mostly original paint. Heads were done 5 years ago but it will eventually need at least a bottom end rebuild. Rust in the sills and right windshield corner. AC disconnected, heater boxes disconnected. The mechanic estimated the value at $12 - $15k. I can probably buy it for $10k. My question is, what kind of value would a car with this many miles have if brought into say a #4 condition? I can't find many high milage cars for comparison. I'm a long time 356 owner and not afraid of some work but I don't want to get too far upside down. I'm just looking for a fun driver.