I have been wrestling with the same question and even considered making the small block swap. I have finally decided though to stick with the slant.
My plans include the super six setup with the 2bbl carb along with a mopar perf cam (or something similiar) to give it a little more umph! I have not planned for any milling on the head or block yet, but that can always change. I also plan to have a nice open breathing exhaust with (I believe) 2.25" pipe and nice rumbly aftermarket muffler.
New gears in the rear will also be something I look into to give me a nice combination of pep and highway cruising comfort.
I will be looking to have something I could drive daily and have fun with. No strip action for me.
I am still in the planning phase of my project so I don't have any more detailed info for you, but there is plenty on this forum. You may want to check into slantsix.org also for more info.