Depends on the mod. I have the 808 reissue and it sounds interchangeable with most of the mod kits out there that I've heard. If I were you I'd just get the Maxon OD 808, since it is closer to the original circuitry and has true bypass.
true bypass is good. I've been replacing my bass pedals one by one with true bypass. I just got the Aphex Punch Factory. Next up. The TC Chorus/Flanger/PM