Thinking about replacing my leaf springs, and I need your advice.

When you finish with your suspension upgrade, we can help you tweak that 225 until it is VERY happy! Cruise on over to the slant 6 area and learn from the guys who've done it!
Rick - thanks for the offer. The 79 HP dyno run was on my previous Duster that I no longer own. I had a speed shop performance tune my current Duster and it runs a lot better, so I'm happy with it. But I'll keep an eye on the slant six area. Thank you for the recommendation!