Welcome to the forum.
I do a kit for the LS engines into the Fiero stick shift. I designed this kit about 9 years ago & there are more than 50 LS Fieros that have successfully use this kit.
It will work for the LS1, LS2, LS3, LS376, LS6 & LS7. It will also work with any of the truck variations of the LS based engines.
As a note on the GTO engines. Both the GTO LS1 & LS2 used a front sump oil pan. All other LS engines used a rear sump pan. To use the GTO engine you will need to swap out the oil pan & oil pickup for any of the other LS rear sump pans. We can aid you in finding the right pan when the time comes.
The kit comes with Video instructions that walk you thru the swap step by step.
The LS kit in it'self is set-up to use the Fiero stick shift transmissions. However, we also have a 6 speed kit that will allow you to use the new G6 6 speed transmissions. The 6 speed transmission conversion kit also comes with detailed instructions. I designed this kit about 8 years ago & I have variations of the kit for most popular engine configurations.
You can find more information on both kits by following these instructions....
There are detailed parts lists & prices on my web site but they're a bit hard to find the 1st time.
Let me guide you to them...... Go to this web page http://www.v8archie.com/v8Archie/Prod2.htm
Then just under the pictures in the center you can click on "LS1"
Then right below where you just clicked will be "Kit#1" & "Kit#2"
If you Click on"Kit#1" & "Kit#2" & read each one of them it will explain what is in each kit & what all is required. As you click on each one of these the text in the large black area changes to tell you about the item you’ve selected. You can even print out those pages.
The same methods apply for finding information about our Transmission kits.
I hope this helps.