You've made a lot of topics in the past few days regarding different program ideas, so my incentive to give you a lot of advice is a little diminished as you may well decide tomorrow this isn't your goal, but to clear up a few things;
-5/3/1 isn't a powerlifting program. The creator of the program has said this on many separate occasions. 5/3/1 is a program for getting bigger, stronger, faster and better. If you want to run 5/3/1, that's great, because it's an awesome program, but it means you have no concerns about combing powerlifting with strongman.
-Strongman is a sport where you have to be strong, fast, and have good conditioning, along with technical proficiency with implements. It's not cardio or a replacement for cardio. You still need to do cardio to get the benefits of cardio.
Are you wanting to train strongman to actually become better at strongman, or is this more about doing some sort of heavy conditioning? If it's the latter, you basically just need to run 5/3/1 as Jim Wendler designed it (which is to say, WITH jumps, throws and conditioning).