The FWD 3400SFI should have the starter on the correct side, and the same bolt pattern on the bell housing. It also has bolt holes for the 2.8 V6 mounts, I believe, as it's basically an updated 2.8. I think you have to use the 88 U-bracket for the front engine mount. At least, that's how it is on a 99-2002 3400SFI. We'll have to wait and see if the 3400SC is the same.
That could be a great engine - even better than the 3800SC, because it has aluminum heads and weighs LESS than the Fiero 2.8, and is actually smaller (narrower, etc.) It won't have near the aftermarket support, but it could be yet another great alternative engine.