I don't think that any of the characters are remodeled after actual mangaka. More over, I think O&O picked several personal traits and blend them into several characters to mix them into "little safe for work yet background stories that standard readers don't know".

To me, Eiji for example is resembling Toriyama, Oda, Kubo, Shimabukurou (as a funny guy and mangaka to create a great character) and Obata (as a mangaka to work a different author than Ohba). But Eiji having no interest in women doesn't actually fit at least neither Toriyama nor Oda.

AM of course is rebuild mainly after O&O. But, I think they are actually based on any writer-artist combo like Hasemi and Yabuki - and without actually looking for it, I'm sure there have been several combos in the past of Shonen Jump, too. (And with the Eiji/Aiko team, we can't be sure if the Tsugumi Obata is either male of female.)

Kazuya and Yuriko partially on Hisashi and Takeuchi, of course - while switching the who's assisting whom, and Yuriko actually publishing in Jump without returning to Shoujo. And Kazuya sharing traits with Sorachi.

.... okay, as I type this and then scroll down for quotes, relies and stuff, I find out that I actually didn't do anything but agreeing to perroloco.