The engine to transmission bolt pattern is the same on both the FWD and RWD motors.
The early FWD 2.8's, the ones with cast iron heads and stamped steel valve covers are almost all the same as the RWD ones, with the exception of manifolds and timing covers. Their starter is almost always on the passenger side. All of the S-10 2.5 4-cylinder and 2.8 6-cylinder transmissions, manual and auto, have the starter pocket in the bell housing for these motors.
The second generation 2.8 and 3.1, and third gen 3.4, the FWD ones with the aluminum heads and almost flat aluminum valve covers, had the starter on the drivers side of the motor. Some of the Crapmaro 3.1's and 3.4's also had their starter on this side. Early Crapmaro 2.8 and 3.1 transmissions had starter pockets on the passenger side, like the S-10, later ones had the pocket on the drivers side. Most of the 3.1's from the early '90's actually had starter pockets on both sides, to allow either starter position.
Newer S-10's with the 2.2 ecotec motor have the same bolt patern for the motor to transmission, but the starter is also on the drivers side.
All of the automatics, Crapmaro and S-10, from 2.2 or 2.5 4-cyl or 2.8, 3.1, or 3.4 6-cyl, will bolt up fine to any of the 2.8, 3.1, or 3.4 motors, but the starter pocket is in the dust shield underneath. You will get a working combination, but you may have trouble finding a good dust shield for the long term.
So, if you already have a running 2.8, 3.1, or 3.4 motor, FWD or RWD, check the side the starter is on. If it is on the passenger side, any S-10 transmission and bell housing will work. If the starter is on the drivers side, you will need the bell housing from a early '90's Crapmaro to go with your S-10 transmission, or get the whole transmission and bellhousing from a newer 2.2 S-10. Or you could try to find the transmission from a 2WD 2.8 equipped Isuzu Amigo. Good luck on that one.
As to the intake, any motor with the cast iron heads can use the carb, tbi, or Edelbrock manifolds. If the heads are aluminum, you'll have to fabricate/ modify an intake to make it work, or turn the manifold around backwards on the motor. This won't clear with the stock FWD timing cover/ water pump setup, but will clear the RWD timing cover/ water pump set-up.
If my camera was working, I could get a picture of every one of these combinations out in the garage. Anyone need some parts?