I vote for using the Holley 390 piece - it covers virtually every base but the rev ranges over 4500. Besides - you already own it. If you feel the need for speed, Charlie's right - you can get an Ebay change-out down the road. I put a 600 cfm Holley 4160 on mine because it was cheap and I've been through the drill of sorting them out a few times on several vehicles. A 600 with a heavy secondary spring doesn't quite give the low rev throttle response of the 390 but still works pretty good.