I would be even more skeptical with the JDM R motor because it has even higher compression at 11:1 than the USDM R at 10.6:1. Then again, I see Turbo RSX-S motors a lot and they've got 11:1 too so who knows. You might be able to get away with it. 91 octane would be kinda iffy.
Jan that's awesome man! Definitely let me know the condition of the stock parts. I'm anxious to hear how the forged parts are on stock sleeves too. Keep up the good work. Keep in touch.