Steve White Motors sells/installs/tunes SC kits, so the OEM PCM might be an option. Might be worth reaching out to them. At the same time, might just be easier to go aftermarket.
Is the 6.4 built? Or are you limiting the boost? The 6.4 pistons are pretty fragile when boost is involved. Not that it can’t be done, but (as I understand it) tune is super important and boost is pretty limited.