[1962SuperStock]

It's common to fill blocks this way for drag-race applications. Of course, the cooling is compromised. Doesn't mean they couldn't be used on the street (I know people who do it), but it's an unknown that would make me choose another block for my project.

Somebody with more experience might be able to tell you that the filled blocks definitely CAN'T be used in a streetcar, but I doubt anyone could tell you definitively that they won't overheat on the street. Wildcard.