I'm Cummins swapping a '74 Duster, thought I'd share the progress.

OK, @Daniel Garcia, here are my thoughts:
1. Go for it. It's your car. It's your plan. And I think it will be cool.
2. I saw where a V10 Viper engine was put in a Mopar (an E Body I think). I wonder if people told him it would never work out? I KNOW that stuffing a 6 cylinder diesel in an A Body is different, but the concept is the same. You are stuffing a bigger motor in your car than it was designed for. Go for it.
3. Will it be safe? I see no reason why it can't be. I assume you have no intention of just cutting and hacking until the big motor is in there. I know that you are going to strengthen and reinforce everything as you go. A heavier car will need better brakes, but I bet you already thought of that.
Overall, I would say this. Can it be done? Yes. It is a matter of how good you are at problem solving and fabrication. As long as you plan it out, take your time, do things properly with an eye on strength and safety, you should be good. I can't wait to see the finished product. Hey, I am only one state away. When it's done, can I come and get a ride?