I have the stock rear leaf setup with a DANA 44 rear and 8" wide rims on my 1950. This arrangement has worked fine for me with an early 350 small block up front.
Personally, I wouldn't rush to radically change the stock rear suspension on my own truck, but you don't say in your post what your plans are for the front suspension of your 51, or whether you want to lower the ride height a lot. Then you might be better off with a coil spring setup to get suspension movement at the rear and keep good rear wheel control too.
