Well first off... *sigh* Im a little drunk so bare with me if I fuck up a little.





The y8 manifold wont fit directly on a z6 head you will have to modify it slightly because it'll have a huge vacuum leak.
a big 16g can get you to your goal, except your going to have to run 20+psi.
a 20g will take forever to spool but will also get you there.
I don't see either turbo being streetable.

Here's how I see you getting this to work...
A DECENT manifold, not an hf it'll break apart from such exhaust flow.
An external wastegate, a FULL 3" exhaust because you'll need every bit of it. You won't be able to retain AC.
A BUILT ASS HEAD I can't stress this enough, although the vtec heads are very good and flow really well. You will need all the VE you can get out of it and as much flow as possible.
Sleeves...
low 8's compression.
FORGED RODS
450cc injectors will work.
HONDATA or other standalone. You wont get there w/o this.

Good luck, best wishes. I don't see this happening for you with out 10 grand and lots of tuning.