There is a big mismatch of years - since a Vortec Tahoe is probably from the mid 90's. The frame of a 90's GMC truck is completely different than the 83 truck.
Swapping the Vortec motor into your '83 is a relatively simple swap, as long as you get all the electronic parts off the donor. You can also switch the Vortec to a carb if you get the right intake manifold. Since you have a 4x4, if the donor Tahoe is not a 4x4, the easiest solution is to switch to a carburetor and use your original transmission and transfer case.