I have the same car same year and am also just looking to get mine running. I have an available 75 or 76 440 pulled out ov a runner, but i would MUCH rather find and use a 68-69 4-bbl 383 (one with stock pistons though). I like the smaller engines, dont need a 440 to go fast, the 383's are just generally stouter, i like revs over low-end torque and probably the main reason that 440 will continue to sit there, alongside my non-running Challenger until i find a nice low-deck... The lowdecks are just easier to work around. I have never had a big block Mopar that wasn't high-maintenance... and there is just more room in the engine compartment with a 383. Weight savings is a big deal for me too... even if its (on average) only 20lbs. I also like the doing more with less idea.