alternative to Comp springs?

Have you considered beehives? I've been running Comp Cams beehives for years with good luck. I've gone to higher pressures, but still have a new set of 26918-16 that may fit your pressure range. They are nice because you don't have to worry about rocker-to-retainer clearance. You can juggle the installed height a bit with +/- locks or retainers. Not sure if you'd have to modify the spring seat any.
I have heard about the beehive style but have never used them, no. They are the next generation style and those part number you said, I looked up, and the pressures are all good but looking at the dimensions, I would need to pull the heads and get the guides machined. I didn't really want to go that far. But good to know that you have had good experience with Comp springs, I can see by the price that perhaps this is more of a quality product. They are a huge company and I'm sure with their buying power they would be able to stock various lines of items of different quality for maximum profits. As I said, you get what you pay for and this is pretty true for anything in a free market.