Marcel, here are some of the things you'll need. Some are from your donor some must be found elsewhere, made or reworked.
3.8 motor
tranny the same as your donor. 4T60, 4T60E, etc.
wiring harness (Fiero and donor)
ecm (donor)
v-6 rad with auto tranny cooler
fuel pump
engine/tranny mounts
linkage and shift mechanism for auto
adapt fuel and coolant lines
exhaust system (keep the first foot or so of pipe from the manifold)
lots of little things.
I understand it is NOT necessary to totally dismantle your car
to do this. Ed's on Dwyer Hill has some older 3.8 which may cough up a suitable tranny.
If you decide not to and are getting rid of your wife's car, I may be interested. I have another car on the way. I don't know how rotten it may be underneath, but it may do for a swap like this.