Goals are mid to low 12's....

A 451 will get you there in quick order, and you could easily source the parts yourself and save about $500 over a "kit". Thats exactly what I did, and my motor has proven to be rock solid. My car is perfectly streetable and runs solidly into the 11's. For an extra $100 or so, you can offset grind the crank, and build a 470. The few hundred you save will be enough to invest in a bigger carb (you're gonna need it).

I spent right around 5k on my motor a few years ago. I used a forged 413 crank sorced off Craigslist. I ran across a 230 casting 400 block on craigslist. Got an Engle solid cam / lifters / springs through Moparts member Jeff Patterson. Bought the rest of it online (Iconn pistons w/ Mahle rings; Scat Rods; Source Stealth heads; etc....)

It was a fun build and I'm real happy with it.