A couple of options present themselves. Since you have a powerlifting and CrossFit background and haven't stated a goal, I am going assume (it may make an a$$ of u or me) that you want to prep for the STO/CRO/CCT/PJ Pipeline and have a reasonable (greater than 8-12 weeks) time to prep. First option is just go with SOPWOD Workouts
found on this forum. Second is to go with the "Guard MC Pipeline Train Up" found on the home page of this site. There are many other options on the home page and I could (and probably should) revise my train up, but this is a start.
Try the PAST and see where you are now. If you are lacking in any particular area, work on it first. If you lack in all three areas (cals, run, swim
) then try a training plan that encompasses them all. As stated earlier, there are many to choose from on the home page and SOPWOD is available on the forums sections.