I would recommend looking for a NAPCO set-up, because it's a direct bolt in. If you want later model running gear, you could do the Blazer frame, but they rarely look right. One way that I've thought about in the past is to take mid-70's Chevy axles, move the spring perches and mount them to the original springs- if I remember correctly, the front spring perches are already the correct width. For a professional job, you should probably have the axles narrowed so they don't stick out so far... that's usually the first sign of a later model swap. I would also recommend using a divorced transfer case like a NAPCO Spicer, or a Rockwell; it would be easier to mount and look original.
Good luck, George
