Paul,
"Back in the day" (that is, two or three exam iterations ago), I was plateaued with the PrepCast Exam simulator at about 75-78% and just stuck. I was sick of studying so I just pulled the trigger and passed with all areas "Above Target." A deeper look at the scores, however, indicated that I either really knew section or really bombed the section, and just my average of right vs. wrong landed my "Above Target! !! A pass is a pass, so it doesn't really matter.
Only you can make the decision. However, my advice is if you choose to put it off until after the July exam rolls out, take a couple of months and do simulator questions to get a feel for the new format.
Good luck.