Just to see what would happen I tried a "fakeroot make-kpkg --bzImage binary".
I started with using fresh patched sources (grsecurity-2.2.2-2.6.39.1-201106042120) and a .config that has been used before.
Since I use debian I ran into a small documented problem (
viewtopic.php?f=3&t=2649)
Simply using "make oldconfig && make bzImage modules" builds a working kernel which can be copied easily. make-kpkg only adds an easy-to-install binary image. I hardly find it worth the extra time and trouble, but YMMV
Perhaps it would be worthwhile if I was using initrd, but since I don't maintain many different pc's I can customize kernels for each computer. Without initrd installation becomes much more simple: just copying the kernel image and the modules to the right place, add a line to grub/lilo and you are ready.
I haven't tried running or installing the newmade deb, but I think it will work since it's based on the same config as my running kernel.
Support for make-kpkg should be asked from the make-kpkg maintainers.
But before you ask support, perhaps you should make sure your vanilla kernel builds correctly using only the tools kernel.org provided: "make bzImage modules".