We finally have an English Dub of Dragon Quest: The Adventure of Dai that’s only available in the UK as of this moment, but hopefully it will come out to other regions soon.
NOTE: You’ll need a VPN to watch the episodes. Windscribe highly recommended and is free (with data limit).
According to these credits screens, it looks like the Ocean cast is doing the voices since Alec Willows (Dragon Ball Z Ocean Dub Oolong) is voicing Brass along with Brian Drummond (Dragon Ball Z Ocean Dub Vegeta) as Hadlar and Flazzard!