I'm DMing a party of five and they're going after Yeenoghu as the campaign's final boss. I've looked online and haven't found any 5e stats for the Demon Lords, but I did find this for a 3.5e Yeenoghu. I've read the official conversion reference, but that's more for player characters and might not apply to extremely powerful beings like this.
I want to create a stat block that would be just as challenging for a 20th-level 5e party (with some magic items and divine blessings) as the block linked above would be for a geared-up 20th-level 3.5e party, but I haven't played 3.5e so I don't have a sense of what characters are capable of there. Obviously a +54 to hit and 45 AC is ridiculous in 5e, but using the quick conversion guide in this question, the resulting Yeenoghu seems too weak for someone with a power level similar to that of the gods.
Are there any official guides for converting very high level stat blocks between editions? Or just a published 5e stat block for Yeenoghu? According to this question, Fraz-Urb'luu has one, but I don't own the relevant book to check it for other Demon Lords.