There’s two custom modes I know of. The OW1 Emulator by Ecksdee. That one has Doomfist back in DPS, Brig has her stun, Cass has flashbang, etc…
It sounds like it’d be miserable but it’s actually fantastic.
Then there’s the 6v6 BalanceWatch by TiredDad. That one’s buggier at the moment but basically has the OW2 heroes as they are in 6v6. Also a lot of fun but role limits aren’t working at the moment. So once you stack tanks, it can get a bit rough.
I haven’t really noticed how they tweaked the health pools on them, but both modes were big fun.
If you want the info for both modes, I have it in this thread.