The Roe has been pushed a ways up, but in my opinion if you want to move beyond 700 rwhp, you are better off with a Paxon or Twin Turbos...
The Roe can probably be pushed to 12 or 13 lbs of boost...but you will certainly need forged rods, pistons, probably striker heads also. I run 5.6 on my Roe and most are running about 5.
With 5+ lbs of boost, I have spent nearly $5000 to get that power to the track, and am still looking for more solutions...I will be at X-Metal in Evansville on the 4th and 5th of June looking for traction, if you want to stop by.
Roy