Have the heads on my 65 Dart 433" R-3 block. Work real well, have had no problems with them at all. Guides, seats, still original! As for the headers, I made adapter flanges, and changed the whole damn approach! As you know the bolts for the A engine exhaust are difficult to get at...especially with larger tube sizes. I used adapters to spread out the bolt pattern for easier wrenching. I used a Chevy Bow Tie pattern which extended the bolt pattern outward and at an angle [front/rear] The middle uses the "three" bolt pattern and in my case I inverted the third bolt to the bottom instead of the top..[fender well headers go up immediately instead of down like chassis headers.] In the end, it was a home made set of step headers, 1 7/8-2-2 1/8 into a merge collector. Hope these pix explain what I have written.