Post some pics that might help.
My car is a 63 Dart GT with a 65 273.
What is changed is the center link, radiator to 22 ", exhaust manifold to headers.
The firewall behind the distributor is cut out and welded with a new plate.
The tranny is a 904 by 76 with floor shift.
Have also swapped to front disc brakes
Do not hesitate to contact me if you need more information or pics.