The 8 3/4 was first offered in 66 and the 273 Commando was a Plymouth only engine offered from 65 to 67. The 8 3/4 would not have come as original equipment in a pre 66 Dart.
Perhaps I am mistaken then. It is more than likely a 7.25" rather than the 8.75" as originally stayed. I have a 3.23 742 carrier out of a 66-67 b body. Would that housing fit with a perch relocation?
