You might want to look at
soma
I don't own one but they seem to have a following. I was looking at one as a touring bike.
Also - many old steel frames come up on ebay - but you need to do your homework before buying.
My advice is to research tubing manufacturers with the primary ones being Reynolds & Columbus, then look at the grade as each offered different grades. Once you know the different grades you can ask what the frame is made of. Not all steel is the same.