Window channel balance issues

For use with a Series 800 Channel Balance, I need the plastic piece that is held by one screw and located at the top of the window. It holds a 19-007 top in place.
Also, if I buy a bunch of 15-018 shoes and 19-007 tops, what tool do you recommend for installing, to replace the existing rivets. Will pop rivets work (aluminum or steel) and, if so, what size?

Thanks, Bert