how sad are you - software - HONESTLY -
just slap a stage 1 kit on and work from there.
(you cant possibly model an engine with so many variables, bores/strokes,
cams, high lift rockers air filters exhausts, advance curves etc, an
a-series engine cannot be compared exactly to a diffferent engine of the
same spec.  )

the only one I can think of is Cartest, its an old dos based program
you might be able to find it on the web somewhere.

Not sure that it will tell you that much, is handy for working out
speed in gears and approx accelerations times etc

-anthony

why did she not say body mods just look in the mini mags