The pcm will be whatever the swap guys use as their easiest to program because the fiero won't have most of the stuff a 3800 car would have had. I think the swap guys tyically used monte carlo harnesses and forget the car they used for the pcm.
Gear ratio in our transmissions is typically 2.93. The way to change gear ratio in an HD transmission is to change the drive and driven gears. These gears are linked by the drive chains (aka transfer chains). For a conversion to a single chain, the 15/16" gearset is known to be weaker than the 7/8" set. The 1" GMR set is no longer produced and appears to be a thing of the past. I'm not sure I agree with needing to convert to a single chain. The HV-093 dual chains are made for the 5.3L version of the 4T65 transmission. Those are strong chains. Your best information on how to build and what to use can be done through Redline Transmissions up there or Triple Edge Performance down here. Search for transmission posts by Foghorn and search out Lee at Redline. He'* the guy you want building your trans if you buiild in Canada, and Dave Norris at TEP if you build one on the US side.
Back to the drive and driven gears.
In the HD: 33/37 plus the 3.29 diff (all hd'* are 3.29) = 2.93 ratio
If you swap to 35/35 (aka non HD gear tooth counts) plus the 3.29 diff = 3.29 ratio
I'm unsure of the tooth count that equates to 3.69, I think it'* 37/33 plus 3.29 diff = 3.69
If you research Foghorn'* build and go that way, you'll be happy for years.
I am still on stock axles and haven't blown one yet. However W body guys blow them up all the time. The H body engine is mounted differently than the W body setup and something clearly helps the H not blow axles.
I drive my car like a little old Grandpa... not. Actually it'* usually a problem when I'm behind the wheel of it. I put on more mileage than the car ever covers, as the wheels are frequently spinning. Ask Sawgunner and Bonneville'N, they got a taste of my "typical" driving in the car.
00 Regal GS: All kinds of cool stuff.