I have seen several diesel swaps, and not many with good results. The cummings, & trans will wiegh more than 2x the normal small block-AOD set up. And, all of it is front wieght. Now, not to say it cant be done, but, adding heavier springs to and IFS is not enough. Even our Wide-Ride IFS has it's performance boundries. The successfull diesel swaps that I have seen move toward more 'work truck' components, such as chev's '73 - '87 platforms, but, they are wider than the '55 - '59, so stance and wheel choice come into play. Please remember that this is just my humble opinion, and I'm trying to help
Have a Happy Easter.