if your gonna re-build it anyways wouldn't you be better of investing in stronger parts anyways?

the pistons would be about the only thing you would realy need to change.
the stock rods (pre AU) are plenty strong enough.
even if only to a set of ACL cast race pistons with a little extra machined off the top to get the comp ration down a little.
something to consider would be coating the piston tops. HPC offer a good coating. keeps the heat out of the piston...

and as with any hipo rebuilt no old bolts. ARP rod and main bolts are the go.
or at the very least NEW stock bolts

With the motor sorted then you need to start looking at the box and diff..

i think i know wat i am gonna do with the box and i thought that it would be enough but wat should i do to the Diff wont the stock 3.45 LSD be enough?

i dont see you having any problems with the diff.
those things can take a hell of beating

you'll need something stronger then a btr box befor the diff breaks.
you may wear out cones though