My old Willans harness had long straps too but they had a metal loop ring ( called strap adjusters ) that you could adjust to shorten the length and pull tight to the rollbar's harness bar. If it comes with those it should work fine, then just zip the the extra belt down like on the pics from Mr. W's Atom. (NOTE: Just forward of the zips you can see that metal adjustor plate im refering to.
http://img.photobucket.com/albums/v146/CrimsonMX5/aristowercz009copy.jpg
I sold my Willans because in only one year of Floridas high humidity the camlock male end plugs started pitting and corroding something nasty. :shock: And for that kinda money? Well... that really bugged me. So i will try out the Takata or go back to my original set of Schroth harness again.