I have a '76 360 from a motorhome in my '68 Dart... My Dart already had a 360 in it when I got it and I just re-used those brackets because the motorhome brackets were a little different. I am also using the same biscuit style mount that came in the Dart. I don't remember it being too much trouble to install
P.S. The original 360 in my dart had the later "smog heads" with the additional holes by the exhaust port (they were tapped and plugged by previous owner) and the newer 360 did not... The same exact headers bolted up in the same spot so yes, they will have the same exhaust ports
