From what I've read, the 3.4L 5VZE swap is pretty simple as far as engine swaps go. Im not sure what you can keep and what you cant but there are engine swap kits you can buy specifically for swapping out a 3VZE for a 5VZE.
88-95 have either a 22R/RE (4 cylinder) or a 3VZE (V6) in them, I think.
I think swapping in a 5VZE is the best option you have for a swap.
Im sure someone with a bit more knowledge on this subject will help out but I do have one suggestion for you.
Try the "Search" button because this topic has been covered quite a bit.