I believe they'd be safe after all the years of use. As long as all the welds look good and you see no cracks when they are sand blasted I don't see any reason for concern. They look really well done to me from what I've seen. The back spacing is right. See what I mean about the rim being straight all the way back? They look nice that way. That step in mine and Jeremy's is for strength,so yours may not be quite as strong. Our wheels were called Duplex wheels for "adding" carrying capacity. I bought two of the set I showed when someone gave me a pair back in the early '80s. The ones that were given came off a '72 single wheel C/30 cab & chassis that had 9.75 rear/8.25 front. The 9.75s had a deeper dish (less backspace) than the pair I bought. It worked great when they were on the back,but were kinda odd when on the front. They cleared fine with 14.50/37-16.5s. I ended up buying another pair that matched the other two I bought. By then they were being sold as "For Trailer Use". I think yours are more like the first pair I had with more dish.
Here are some other pictures. Check these out on a spool dolly:
Those I showed above I had powder coated glossy black in the '80s,then stripped them again and had them done in white in '91. They just recently came off of a truck after all that time. Yours will look as good as this 8.25 set after sand blasting and powder coating (or a good paint job). I gathered this set from all over individually in various condition. Some were much worse than yours:
