What you want is a completely stock engine.
I'm not bashing you. I'm being completely serious.
If anything, get groupN motor and transmission mounts, but skip the pitch stop, as it's not any different with the groupN.
Don't get a lightweight flywheel or a crazy clutch setup on a car that doesn't need it. You will hate yourself every time you have to change gear in your daily drive.
You can't build that engine better than Subaru did, especially since you aren't going to run a standalone/tune.