There is a 3.4 litre stroker kit available. Lots of dollar though and serious power targets are a must to warrant the expense.
Have a read of big power threads like JamieP, LeeP, Michel Lane et al. There are a lot of good references to follow up on for reasons to go down this route.
Smaller rebores like 87mm are usually carried out to repair / renew big mile or damaged engines because it's cheaper than replacing the engine.
A Supra engine has been proved reliable to over 600 bhp without modification to internals on a regular basis. Compression and leak down tests will prove your engines' health at a far cheaper expenditure. Then you can bung just about anything on it and be happy in the knowledge that it won't break.