I have a 5.7 in a 63, but I'm using an AlterK. I don't see any reason you couldn't do it with a stock K frame. I used Jeep srt8 exhaust manifolds for clearance and price.
I have been checking out your build thread for inspiration. Awesome build BTW. I wanted to use the stock k to keep the overall price down, but after seeing your build I think I will just save up and get the alterK. It looks like a much cleaner install and probably rides a lot nicer than the t bars.