Might be time to switch to an 8" Converter and as others have said the Solid Cam is maybe a little small, and you'd probably benefit from a bit more lift.

TBH I'm happily surprised for you that the heads are picking you up as much as they are.... with 'only' 440 cubes. Have your shift points changed?

To work the 270's you may need at least a couple 100 more rpm.

Does your charger have a spoiler on the front? B bodies pick up a lot of air underneath so they might help your top end MPH.