Porting a slant six head

I have this de-burring set http://s675.photobucket.com/user/jhason2/media/Picture585_zps643b3c34.jpg.html I have been told that I will need a long reach set to get all the way up inside the runner of the head.

Admittedly I have not tried these yet but yes they do look short, where can someone recommend I get the set that I need and which specific cutter do you suggest.

These can get pretty spendy and Id rather not buy an entire other set if I do not have too. Thanks