My goals are the same as yours. I do road course track days and DD.
Just buy a new short block from AWD Tuning. Fresh case, hone, new pistons (I went with JE). Manley H beam rods are a good reliable option for your power goals.
The 5MT will be a weak point.. it might last for awhile at 400 wtq, but I decided to go with a 6MT for better ratios, better diffs, and stronger to hold up to higher torque.