converting a 3/4 ton to 1/2 ton

[GMC70c20]

I have a 1970 gmc c20 that I eventually want to make into a 12 sec truck, I dont really care to much baout the handing of it, it would just be somethin fun to drive on the street and take to the track every once in a while. I thought I would get rid of the 3/4 ton spindle and hub assmeblys and use a 1/2 ton setup. I thought about getting a conversion kit but they are pretty pricy os I was goning to find a old half ton and just robbing the spindles off of it and using that assmebly with my 3/4 ton control arms (because they are identical). Would it be better to just spend the extra money and get a conversion kit or find a old truck for cheap and use the stock stuff?