For those searching this subject.
An update to this post if you want to put an Astro/Safari van power steering box in a 49-54 Chev, it is easily possible.
First you do not have to reverse a Astro van box it already comes like that from GM. There are two different PS boxes, the 2WD box is reversed to the AWD box. The 2WD box is the one you need.
Second you need to re-index the pitman arm. You will need to find an offset pitman arm so to make clearance from the exhaust to the pitman shaft of the box (only on a V8 conversion).
You can find these kits on ebay but it is much cheaper to make your own brackets.
looks like a nice conversion, putting my engine in my truck gives me problems to fit in a power steering box. it's a 3100 1949 paneltruck. by any chance any idea what box would be best to start with.,?