Which Carb next?...351 Cleve

My 79 Ozzy Falcon has a 351 Cleveland (yes it is, there are heaps in Oz and NZ). The guy that dyno tuned it said "ya carb is worn out, dont rebuild it, throw it and buy a new one". It currently has a Holley 600 sq bore vac sec.
The thing is, i've done a few drags recently, the best being 15.8. Now i'm getting a bit less concerned with economy and more concerned with going faster.
Most people said "get a 650 DP". I would like to hear other opinions. But would prefer to stick with Holley.

Cheers
Phil

XEN, is the 351 stock ? what kind of RPMs do you buzz it to ?

Pretty stock really. 4V cam, alloy intake manifold, tri Y extractors.
Probably maxing out at 4200 rpm.

I did the maths equation on the Holley wesite and it came up with about 425cfm.

I think Id use the 570 Holley Street Avenger. John