Personally, if you are going to grass the area over, then I wouldn't worry too much about large pernicious weeds, as they shouldn't persist for too long, once you start mowing on a regular bassos.
I had 6-8 foot docks and thistles on one of my, previously neglected lawns and they soon disappeared when the mowing started. I still get a few patches of clover and daisies but I'm happy to leave them for the butterflies and bees.
Hope your efforts pay off with good results!