I skimmed the datasheet and didn't see any mention of an open drain EOC output and there is no special mention of EOC in the DC electrical characteristics.

The ADC0808 seems like a part that should be avoided. The TLV571 is a better alternative - it outperforms the ADC0808 in every way at the same cost, plus it has an internal oscillator and is software triggerable. The TLV571 isn't available in DIP, though so it may not be as friendly for experimenters.

- Lee