First of all you cannot have it all, everything in life is a compromise.
Maybe in the future with variable compression engines....
Well at 8 psi, stock compression with no spacer, (i guess) no intercooler and no water injection your engine will have problems especially in the summer.
For me the max psi with stock gen1 engine should be 6 psi especially now that you will need to trim the warped head which will raise compression close to 12:1
My opinion is to check the fuel system first (i think you have done that), install the head studs after checking the head for flatness which btw may increase compression to 12:1 or more and finally install water injection (for me this is a must) and remove some timming at 7-9 Krpm.
The best way to correctly adjust fueling in a gen 1 Hayabusa cheap enough is with a pcv pti btw.
Also i would not use a spacer for lowering compression as it will mess the quench area and the engine will detonate easier, get the correct turbo pistons when you find the right time.
One final word, the engine should never ever loose coolant in any way, if yours do and it is not caused by a leaky radiator or leaky hose or a bad radiator cap or a faulty water pump then the head gasket is gone and it needs to be replaced.