Its something to really try to understand why you get this effect. My 340 also went almost 2/10ths faster with that 850DP rather than the 750DP it came with yet I was only using around 6100rpm tops@the traps at the time on stock unported 2.02 heads and only 10:1CR, headers and a strip Dominator with 2" spacer so a nothing special motor.

An engine will only pull the air it needs with a certain head design/bore/stroke/rpm etc. yet a bigger carb always seems to work at the strip defying any method you care to use to calculate its needs. But its not always the case on a dyno, We ran a 950HP holley on a 589ci street wedge motor, only 10:1, had race heads that probably flowed in the 340cfm range@ the solid roller cams max lift of .625", and a 440-2 intake, it pulled 1.9hg vac@wot at 5800rpm and went to 2.0@6000 suggesting the carb was too small, yet when a 1050 Dominator was tried with an adapter it only made 3hp more, that could've been because it wasn't dialled in or the adapter?. but I have read a few times that on similar big ci motors of that size a Dom only made a max of around 10>15hp more if that than say a big 4150, its all combo related I guess but there is no real reason why 1 carb of only 100cfm more can make a 2/10ths difference on a smaller motor and on a large motor that actually needs at least 1050cfm+ of air according to calcs and a dyno it doesn't quite work that way, perhaps at the track it would be a different story and the better way of trying things out. Maybe things need stepping up to 2 x carbs for real gains on big ci motors with enough valve lift of course and rpm. Or perhaps my thinking is somewhat off?

sorry for slight hijack