Imagine you are them, a business out to make a profit . They honor the warranty till 2021 its 2024. Yes the engine sat for 3 years and they wouldn't say you are lying but, they don't know if you are telling the truth. Maybe the engine sat with water in the water jackets and it froze etc. They just don't know. Maybe they'll be nice and rectify it but ,they don't have to... at that point they would be "being nice" Being nice cuts into profits if a business does it every time they honor a warranty that has expired. Its another point of view. A 318 LA block is attainable , disassemble the innards and have the machine shop machine in the piston to bore clearance and reassemble.