Where to start?

My 416 has a small miss at constant rpm. Especially noticeable between 2500-3000 rpms. It has msd billet dist that's locked out. Msd blaster 6 al and wires. Ngk racing prov 7 plugs,and Quick Fuel 850 carb. It doesn't stumble on acceleration.
I recently changed power valve to 4.5 due to running really rich. I noticed it more after swapping power valve.
I'm not sure if I have fuel or firing issue. 150# compression on all cylinders,valve lash good. Custom grind comp cam 245/251 556/573 110 lsa. I'm running it at 24* timing due to street driving almost totally.
Swap carb first? Already swapped cap and rotary.