This may help
that was on BAKES r34 GTR - the engine just had bolt on's similar to yours, but a restrictive exhaust which hurts the -5 result a fair bit.
http://www.skylinesa...gtr/page__st__0
If you wanted a -5 set-up to be as/near responsive as stock, you would have to look at VCT or a stroker.
However, if you look at 2.6's that are built for a -5 setup (ported head, 260 cams, 4"inch exchaust etc), the power curve virtually follows a -7/-9 curve...just with a significantly higher peak. Not sure how the revability is affected...will know in a couple weeks once my -5 build is finished & tuned .