Like any other .src.rpm you should be able to rebuild the kernel with the rebuild option to rpmbuild. I assume you already installed the kernel source. The result should be a rpm identical to one you could have downloaded. But you had fun playing solitaire while you waited.
mkdir ~/rpmbuild/kernel/BUILD rpmbuild --rebuild kernel-XXX.src.rpm
Unfortunately this will clean everything up when it's done and it takes a long time but it proves that you have everything you need to build the rpm.