You are headed into some interesting and complicated territory there.
First off, it will probably get you LESS bottom end, as that is what
the 8-valves are known to possess. More power, probably, if you can
work out the fuel delivery and what sort of intake system you can
arrange to make this swap work. You might check out some of the
English tuner mags, as I believe the Corrado was available in Europe
with exactly that engine, minus the G-Lader.
In any case, you are probably going to need the assistance of
someone with a dyno to get it all happening, since that stock
computer isn't going to like this at all.
If you are on the East Coast, try Dave or Ed at NGP in Maryland.
Also, have you considered just dropping a 1.8T in there. It may be
much easier to integrate, but those folks can tell you far better
than I.
Good luck!