just like the heading says would the engine and tranny out of a 89 buick lesabre be good enough for the fieros sportiness?
for example is the tranny geared to low for high end speed , ect. I ask becuase i found a great deal on a v-6 model for REAL cheap.

Most of those cars were 2.84 final drive, with roughly the same first three ratios as a 3 spd auto 4 cyl Fiero, but with overdrive. The first three ratios should be about what you are used to already but with the added grunt of 3800 torque and an overdrive to make top-end cruising a lot better above freeway speeds.

if i decided to swap the guts of it to mine , what all would i need for the swap ?

Engine
Trans
Engine wiring harness
ECM (Computer)
from the Buick

anything else? What about exhuast stuff , will it need to be fabricated.

Ryan has all the info you need at
http://dtcc.cz28.com/swap/3800.htm

I too have a 89 3800 from a Olds 98 sitting in the garage. I kept the ECM, trans, fuse block, etc. I am just waiting for the right donor. Don't forget you will need:
axles (can be had from A body 4 speed auto)
a way to fab up the fuel lines to the fuel rail
accelerator cable hookup
you will have to dig around in a parts store to find hoses to go from 3.8 in and out to Fiero coolant tubes
You will need pinouts of the C500 and C203 to integrate the neutral safety switch, oil press, SES light, tach etc to the Fiero.
Fab up a reversed shift arm at the trans to shift the 4T60 with stock shifter cable
Fuel pump if swapping into a 4 cyl fiero
tach recalibration if swapping into a four cyl fiero
Motor mounts and mount brackets (I am currently trying to figure out how much of the 3300/4spd A body mount stuff will direct-drop into a Fiero.)
A neat way to reroute the wiring harness towards what will now be the front of the engine.
Swap valve covers to put oil fill in the rear
move dipstick to accomodate trunk hinges etc
A neat way to route the 3800s ECM harness through the firewall.

.....A few other things I am sure I am forgetting and purposely ignoring like cruise control hookups and A/C (which is for wusses)

This should get you started....

Kurt

Here's pics of an 89 swap to inspire you:

and

is there any build up threads on this , with lots of pics. I have never done an engine swap , so i will need all the help i could get , lol.