Ok, you gotta clear up what exactly you are looking for.

So far you have mentioned:
4.3
3.8
and 3.4

If you have the 3.2, anything except the 3.2/3.5 block will require a drivetrain swap in order to work. Along with moving/making mounts, changing driveline lengths and all the associated wiring.

So...let's talk about this. What is is you are exactly trying to do? What experience do you have and what facilities/tools do you have. It is really easy to get in deep with an engine swap.

Michael