There are Thorley "D" Dart headers, and Laysons has shorty tri"Y"s. They each have their pro's and con's.
63 Darts were not designed for v-8's so fitting one in is a bit more of a chore than 64 to 66 early "A's, but it is doable. You will need a 64 to 66 K member with a v8 center link.