there's more than one way to skin that cat,
obd1 '7730 PCM
-Done a bunch, relatively simple, old school, works
-becoming more difficult to find competent tuners to work with
-needs a trans controller
obd2
-also done, but not as much with a 3400, more frequently with a 3800.
-not as many tuning options
-works with the 4t60e/whatever the donor came with.
-will require HP tuners, or a DHP Powrtuner, which can be expensive, or hard to find.
Megasquirt/other standalone
-most tunable option
-most tuners will work with you on it
-less support on this forum, but has it's own dedicated forums.
-will require a controller for the transmission, could use a microsquirt.
Wiring diagrams are available here:
http://www.gmtuners.com/files/index.htmHardware:
The 3400 can accept modified stock V6 mounts, if you were to install it with a manual transmission, you could use stock trans mounts. being that you want to use the 4 spd auto that comes with the engine, you'll need to research mounts. My 3500 swap used a 5 speed, and I'm not as well versed on the automatics.
the alternator is going to be very close to the stock dogbone mount location and will probably require a decklid notch, you can use a stock 88 fiero timing cover/front engine accessory drive, but then you lose one of the crank position sensor mounts, and the OBD2 computer will no longer work.
I made my own low mount alternator, but something like it might not work with the automatic

I drew the top header flanges in this picture, because the other off the shelf options were trash

More details in the thread below, the file is available for download, and can be cut by a laser cutter like OSHcut relatively inexpensively for a well designed flange, they're best suited to a 1.5" OD tube swaged to fit inside the flange, or welding your desired pipe to the face of the flange. if you use them and like them, and want to buy me a beer for the effort I put in, my paypal info is on the drawing.
http://realfierotech.com/viewtopic.php?f=3&t=21666https://drive.google.com/dr...YB3JtmcWl4JwRS4fHD6rthe stock intake will fit in the fiero no problem, but FYI, the can intake has a gnarly hump in it, which isn't very good for top end power. while you have the engine out of the car, it wouldn't be a bad idea to install new lower intake manifold gaskets, they have a tendency to fail and puke coolant everywhere, and will be easier to replace with the engine out, but not really hard to replace in the car either. if you do, the pushrods are two different lengths, the intake, short, the exhaust long, don't mix them up!
Hope this helps.
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"I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."
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