32/36, is what the "direct" replacement would be, but i have ran a 38 on a stock engine before...
be fore warned... Webers may say they are just install and go... but i have installed many and have had to tune them all to match the truck they are in...
I have also seen threads here and there about de-vacing the stock carb... yea might give that a try because the stock carbs are actually a nice unit offroad...