I'm wondering, what 8-X value would I need on the Sockfolder room, for the last room of 8-4, to be able to get a 458 with two frame setup. (at standard, low 459 pace)

do bbg and you don't need to worry about 8-4 values.

Sure. I want to worry about 8-4 values, for 457 eventually, and I would like to know what I could do without removing another framerule.

So, does anyone know?

Kosmic's 8-4 IL WR (44.493 sec) corresponds to "8-J" on Sockfolder's ROM. Compared to that you can lose 58 frames and still get a 458 (4:58.990). Hence, "8-3" (equivalent to an 8-4 IL time of 45.458 sec) is barely fast enough.

Thank you @Marikh