I’ve hit 318 cfm with my Edelbrock heads with a ported super Victor on my old 408 that ran 9.60’s. The super Victor at that time helped calm the air speed on those heads. On my current 408 with the same Edelbrock heads I have the nicest Victor340 that I’ve done to date. I’m betting it would run some very low 9.30’s but I run all 1/8 mile now so it’s been 5.98 in not so good air. It’s running better than my old 360-1 Indy headed engine right now but it only had a solid lifter cam. I will be reworking those heads.