Can someone recommend a V8 Crate Motor?

Looking to upgrade for more power. Currently has stock 273. I have a modified 8.75 Sure Grip Rear and Factory Disc Brakes installed. High horsepower is not an issue. Have been looking at 408CI 445HP/500FTLB engine by Blueprint Engines but am concerned that drive-ability would be compromised. I'd like a relatively quiet smooth idle. Not necessarily monster power, but a good step up from the 273. Would like to stay with an LA block. Any thoughts or recommendations?

This will be going into my '64 Dart Convertible.

Thanks,

Curt.