i am putting a 350 in my 1994 isuzu pup and im not sure of what all ineed to do

Do you have the Motor? Do you have the tranny? Do you have the Wiring and such diagrams? You are also gonna need either a kit that helps in relocating the mounts you are also gonna need to upgrade the rearend gears and possibly as far as reinforcing the housing. Take some measurements for the driveshaft and the location of the cooling fan.(electric of course, pretty sure there wouldn't be enough room to keep the stock fan)