A V8 into a 63 valiant

I'm still researching it, but all the details are sketchy. A lot of people refer to putting a 383/400 into an early A body, but when everyone chimes in on what they did for exhaust, half of them are working on 67-76 cars, lol. I have read that angle milling the hp manifolds works on 67-76, but not on early cars. Back to the research. Eric L