Stock internals have been pushed as high as 20 psi before breaking (on a supercharged 3.0). It's not the internals that go first, it's head gaskets, or head bolts. If you have decent head bolts and fresh gaskets, the 3.0 can take a lot of boost.
I don't know if he's a member on this forum, but there's a guy on most of the Ranger forums that goes by The New Guy, or CarefullySleek (depending on the forum) with a badass turbo 3.0. At last check, he was running 10psi on a motor with stock bottom end and lots of breathing mods. He's got some videos on youtube you should check out.
E85 is a good idea, but make sure you have large enough injectors to handle the e85 and the amount of boost you want to run. I've got 42lbs injectors in my whipple supercharged 3.0.
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