Timing chain tensioner for a 360 magnum?

Hey guys I'm running a solid cam with quite heavy spring pressures in my 360 magnum. My timing Mark jumps around quite a bit and I'm guessing it's due to the feed back from the spring pressures and timing chain is not tensioned as it never did it when I ran a hydraulic cam.
Does anyone know where I can get a timing chain tensioner from to suit a magnum.
Thanks