That is definately a 63. Of the 60-66 trucks, 63 is my personal favorite. It is the only year that has the wrap around windshield AND the newer chassis that gives you multiple and cheaper options for upgrades or stock parts. In 63, they started using the "ladder" chassis which remained relatively unchanged until 87. (I think). Other with more knowledge will chime in.
I'm an inline guy, and a hopped up 250 or 292 would also be a relatively cheap and easy thing to do with that truck. The inline engines available that year were the 230 and 250. I don't think the 292 was a choice then but would still be a relatively easy swap as it shares a similar design/interchangeable parts with the forementioned engines.
As far as what it is worth - hard to say. It varies with the region your in. I would also need to see it up close and personal. According to your description, I would be willing to pay somewhere in the neighborhood of 2-3k. Good luck and keep us posted.
