lots of options, depending what your skill level is.
Armstrong is by far the cheapest option tho
you could do the hilux powersteer box mounted on your original steering box mount and retain the push pull setup with idler or go to a surf box and go cross over steer, or 70 series box or 60 series box or as skid mentioned the cressida box... lots of options.
try searching ORE and you will find a lot of info on many set ups
