Hi had a similar idea, and used the Sierra XR4x4 2.8 doner car for my build. The main issue you will face is the size of the gearbox front output. The front final drive shaft would also sit in the middle of the drivers footwell. You would have to make some major mods to the chassis or fabricate a chassis around it.
Also the front drive shaft run through the sump and the diff would sit where the side rails are on the standard chassis
Good luck with it, lots of photos on Year 1 of the gearbox I assume you want to use.