The 3071R-WG that SZ sells has a clipped turbine to fit in a T25 turbine housing. The full size 3071 is a T3 and has a 60mm turbine wheel.
SZ claims that their 3071 kit spools faster than a GT2860. If you could find a way to modify your turbos for the .64 housing that would be the best way to improve your spool.