The 5x200 session is going to kick your ass, and doing it the day after speed may not be feasible, especially if you expect to do more speed type work the day after 5x200. Try it and let us know how you feel though.
As for lengthening the runs in the second GPP block, I’d go the other way around and start with longer runs for general fitness and conditioning, getting more specific (and shorter) as you get closer to the race block.