I would say your good to go as is.
Trail or MX port is going to be a low to mid range port job so you pipes will be fine, weather you do a 4 mill or not. Those carbs you have will aslo be good. I wouldn't go to a 33mm pwk unless you get a dune port job.
A 4 mill does gain you more mid range, so you could get a more agressive port job and still have more or just as good of a midrange as a stock stroke trail port. That way instead of being all low end it will rev out more, but still maintain a decent mid range.