So I'm not sure if there are any members who haven't done these ach but, there is a simple way and place to find all the profiles you need to finish them.
Go to SEARCH scroll down and in the bottom left hand corner it allows you to search by level. Start at LEVEL 1, when it appears hit PAGE 100. most of these profiles are long gone. remember they have to have a profile pic to qualify. When you finish the page Hit 99 and go backwards from there. You have less chance of hitting repeat profiles.
By holding CONTROL and tapping each profile you can open them in new windows quickly then simply go through hitting the invite button on each profile. When you hit the last page, hold CONTROL again and tap the W button to close them. Easy as pie. good luck.55