Yes mate very do able for coils i think you would be better of using 80 series front diff so you can keep the 6 stud rims easy to get big and wide aftermarket rims for
For the cab this is a 79 series cab on a 75 the 75's have a shorter chassis than 79 so you will have to remount your tray or move it back about 100 mm or so
pinkfloyddsotm put coils in his 75 series looks aboslut nuts