From what you said, this is just a "temporary" motor, until your "Good one" is completed. Knowing that, I would clean up the motor the best you can, and unless the head gasket is 100% blown, I would go with it. Clean as much rust as you can, wipe everything down, and mask off any holes or ports that rust and dirt may end up when you clean it up. Some people go overboard handing out advice when its not their money or time... I'm not saying people are purposely giving bad information or advice. But over the years I've noticed some people go way over the top when giving advice. I mean come on It's a CHRYSLER, of course it will run!!!