Mismatched Cam and Heads?

So long as they pass muster (like the pressures). I know for anything beyond 230°@.050 in a modern fast rate, they are not strong enough by themselves. That's a Comp XE274H, the Lunatis beyond their 268, etc. Those all take true dual springs. If they have worked for you, that's great. I've used one set of OEM Edelbrocks. All the others got better ones.