Mjolnir

My VR4 has been running 200kw at the wheels for a few years now with standard internals/ cams on E85 running round 20psi. A compression test the other day showed around 95-100psi across all cylinders on WOT, not exactly great. 

At the moment I'm saving to put in a mechanical diff and 4 bolt shafts, and in light of this compression test after that I figured I might as well give the motor a rebuild, it has done 170k clicks after all. 

Im thinking of aiming for 250ish kw at the wheels on E85, and at least 200kw on 98RON with, wait for it, a standard motor.

Can anyone give me some advice on if this is possible? What are 6 bolt 4G63s like at making this sort of power. Would bringing the engines compression back to standard allow more power to be made? The car has most other things sorted for bigger power:

-ECM Link

-910cc injectors

-walbro in tank

-3" turbo back with cat and muffler

- big 16G

-jap spec intercooler

-ARP head studs

-multilayer metal headgasket

would it be possible to even get 220kw maybe on completely stock internals with E85? Or will I need more exhaust/turbo flow?

My initial plan (if the bores don't require machining, otherwise this plan is going out the window) is new set of wiseco rings, race bearings, ARP mains and rod bolts, everything else internally left standard. Might also go for wideband O2 sensor for extra tuning ability. Has anyone been done this path before, obviously id rather not fork out for forged stuff yet if i can avoid it.  Also interested in seeing how much a stock 6 bolt will make, as SR20 internals with the right mods will hold near 300kw.