Wouldn't know without looking at the actual health of the engine. Your tuner would know what they are doing. Best to keep it as safe as possible. My tune isn't overly "Safe" its a bit agressive but i have had a ground up rebuild.
That is a nice curve though. From what i've seen most cars run around the 270-290 mark that are still stock internals.
Honestly until you even think about doing internals i wouldn't put in on E85. Has the motor been rebuilt previously? if not 20 years is a long time worth of thrashing haha.
I should have taken some photos of what my motor did to itself...
Edit: as zebra said. It's fine. Im pushing 21PSI through mine...