The issue is the early A's are much more narrow than the 68 and up stuff. So everything is squeezed in.
I love the early A's but that narrow frame makes everything that much harder to fit.
I once cut up a set of 5303 Hookers to make them into W2 headers form my 64 Barracuda. I wish never did it. Hooker will never make the 5303 or the 5322's again and that's a shame.