Man I was in your shoes, just about made myself sick trying to make this decision. I ended up going with Borla Pro XS using 3" with a x-pipe then into 2.5" tail pipes. I liked it so much I did the same thing to my 57 and my brother did it to his 67 Camaro.
https://www.youtube.com/watch?v=rccR1LRSMqw
https://www.youtube.com/watch?v=xpAOO...13HlQPisu3JZJF