I suppose some people can put RC stuff in a 500 series, I think the 400 series is a bit tight. There are other forums for RC stuff and it might be better if you look there. Hippocket also has there forum broken down into categories, and you can search some info there on RC builds as well.
I really do not do RC at the moment, and would not be of much help.
It is good you are getting a good glide. Sometimes you will need to add a fair amount of weight. The model NEEDS to be balanced, and when it is, it WILL glide... That is as long as it is not a brick!
Good Luck, Mitch
PS look over the "posting pictures" post for info on how to post pictures!