Lukecrumpy

Hi, I would like to put a 5 speed In my 1980 18R RN46R 4X4 HILUX (pickup in the USA). Low gearing in the first 2 gears is a must, as I live in steep 4x4 access area. It is currently fitted with a Weber 32/36 so would like 3rd to have some pep. currently 2nd has the most Power. Tossing up between a w50, w55 or w56. any input appreciated. cheers