When I first got that Dart it was missing the motor and trans but had the original BB block radiator, a se of 1 7/8 Hooker fender well headers and the original complete motor mounts.
I found a 440 block that had the correct mounting bosses on it and used it to race that car for 7 to 10 yrs
A friend of mine several years later bought a 1969 M code fastback Baracuda from a guy in Montana that had, according to the seller, the original block that had two holes drilled and tapped into the front of oil pump boss down low for the 383 mount to bolt into