Loving a slant is a state of mind, not a power house (unless you turbo/EFI it with one of Bryce Gill's kits). I would not say they are not powerful if you hop them up. The are quite powerful.... compared to a bone stock wore out one. There is not once I wished our Dart had more power. Get the compression up to something respectable a nice Dutra RV10 type cam grind with 2 barrel and it will run respectfully.
I'm slap giddy every time I drive Vixen. She's a barrel of monkey to drive. I just got back from a friend's house helping him adjust the valves and tune on his nostalgia dragster and I had more fun on the ride over and back home. lol