Yes, there is some concern over the later blocks with casting number ending in 557. It is said that they have thinner casting and are therefore weaker than the earlier 400 blocks. I know from experience the 400 block in my '77 Grand Safari Wagon lasted to 165,000 miles, when it needed a valve job. I would not hesitate to use the engine you refer to.
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BONESTOCK GOATS
'64 GTO Tripower Hardtop (Wife's Car)
'64 GTO Tripower Post Coupe (My Car)
'99 Bonneville SE Sedan
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