The original ELIZA ran on an IBM 7094 mainframe, in the 1960s. That machine had 32K x 36-bit words, and no support for byte operations. It did support 6-bit BCD characters, packed 6 per word, but those were for string operations, and didn't support arithmetic or logical operations.

This means that a directly translated 40 KB Z80 executable might be a tight squeeze on that mainframe, because 40K > 32K, counting words, not bytes. Of course if most of that size is just 2-bit weight data then it might not be so bad.

ELIZA running on later hardware would have been a different story, with the Z80 - released in 1976 - being an example.