Educate me on early A vs 67-76A

I'm looking at 2 Darts as projects - both 2dr post - one's a 65 the other a 66. The 65 is a 273 auto, the 66 a roller. What are some of the differences between early A and 67-76 A?? I have a 75 Scamp.

1) Does the early A have the same K member for both /6 and V8?
2) How about spring mounts and springs in general - can early and late A interchange?
3) The 65 would have the older 727 and cables - how difficult is it to put in a newer style 727? Is the support bracket different?
4) I see that there are big block early A's - how about headers and engine mounts for this application?
5) How difficult is a 360/newer 727 swap in an early A - what are some of the major issues??
6) Front disk swap - what are the major issues?

Thanks!