Last time I checked (at time of writing, a day ago) the Converter Multiblock is unobtainable due to HSLA 980X (used in one casing) having no recipe that I could find.

I yearn for my big hot metal pot.

Also, weren't we done and over with the GT++/gcym-flavoured alloy faffing?

its obtainable in the arc furnace: look up molten HSLA (the molten versions don't show in the materials page idk why)