If you add this line to the bottom of your main.lua file, the furnace will unlock with the same tech as the 3x3 version
table.insert(data.raw["technology"]["advanced-material-processing-2"].effects, {type = "unlock-recipe",recipe = "electric-furnace-2x2"})
I'm sure with a bit more work you could actually get it to scan the technology table and find the tech the 3x3 unlocks with so that it tracks with Mods that change the default techs
