The stock block itself is pretty strong. I have seen reports of a few breaking at the number four head bolt when pushing over 700hp. As to the stovk bottom end there's been people run 400hp+ out of it for periods of time.
For a bunch of handy info on the 3SGTE and the MR2 in general take a look at http://www,mr2oc.com.
If you wanted to make it a little stronger a set of forged pistons and a MLM head gasket (e.g. TRD, HKS) wouldn't go astray.
Beyond that you would be better off spending money on other things such as aftermarket engine management and bigger turbo and then once you've done all your bolt on upgrades get the manifolds portmatched and the head cleaned up whilst testing with a flowbench (+cams etc.).
i have done the bigger turbo its a trust t67 and haltech e6x
just wanted to know how much the stock block well take before
i blow it
any info is much appreciated
does anyone know what the TRD engine mounts are like on the car
is it a rougher ride or is it harder on the engine at all
and how strong is the gen2 185 gearbox