From my Aussie lads, there is a driveshaft tunnel and center differential mounting point in CBU lancers. The Rear axle and ACD will bolt right up. From what my Aussie lad shared, he transplanted 4B11T from ralliart to his 5 speed manual VRX (Lancer GT here), the fuel economy is slightly worse than before. Manual does help alot in controlling the fuel economy, plus its still FWD.There are people who have done 4B11T swap in Malaysia on Lancer and Inspira. Perhaps you can find a way to lock the gearbox like how people do it in Evo 1,2,3 or VR4 gearbox. It depends on the underbody of your Lancer whether does it have the transmission tunnel section for you to fit in the whole differential. But with that engine, you are almost going to have a real Evo kind of maintenance for your Lancer. No longer as cheap as it used to be.
Adjustables and 4 pot from Silvia S15 definitely count as mods to me.
I don't think the SST could be modded that way, but i don't mind look into it, just for education.