Here's food for thought:
New 426 crate Hemi, soup to nuts, plus new K-frame/motor mounts, etc. etc, etc - Minimum $15K plus labor to install.
Keep your 440 and add a 6-pack intake - About $2,300, and you can do it in your driveway.
To me (and I'm biased), a 6 pack has just as much Wow factor as a Hemi. I see more Hemis at shows than I do 6 packs, at least where I live.
Short story but it's actually pretty funny. I had my car at Autorama this year with several others from the Mopar club, including a nice 68 Charger with a crate Hemi. We both got class awards, and at the end of the day, the owner of the Charger made the comment (as he was holding the same plaque I had), "$15K and this is all I get", obviously referring to his Hemi.