Ash, you dont need to take the head off to do the valvesprings, dont make a simple job harder by ripping the head off.
What A/R is the exhaust housing, is it a total stock XR6 turbo with internal gate? arent these 1.06 housings, may be a bit laggy, be interesting to compare it to .82. let us know the results.
did you sort your oil problem out?