Valve spring help

Ok. I rebuilt a 318 with Z heads. I installed a comp cam that is 525 lift 300/260. Problem I am having is valve spring pressure. I replaced the springs with stock replacement ones from comp cams and is not working. I found out this cam calls for a 115lb spring which is a double spring which requires machine work on the heads. Question I have is if there is a single spring that doesn't require machine work with the 115lb of spring seat pressure that I need that won't coil bind at high rpms?