Big small block

My car project is going to be on hold for a while so I will have all kinds of time on my hands to sit here and "paper" build things. First off, my goal. I would like a car that runs on pump gas, is somewhat driveable, and gets at least in the teens in mpg. Would like to start out running high10's-low 11's (been a long time since I have been down a dragstrip). But as time moves on I would like the et to drop into the low-mid 9's. Car is a 69 Dart, cage certed to 8.5, mini-tub, springs relocated. I realize that I will probably have to ditch the springs to reach my goal, but will cross that bridge when I get there. Car has an gm4l80e in it (it is staying) and a Currie 9+ rear, which is also staying. Original plan was a 572" Hemi, complete with an Crossram set up for EFI. But, now I am not so sure. Have been tossing around the idea of a turbo setup, preferably a twin. Without chopping up the fenderwells:banghead::banghead: . I realize that this will be almost impossible with a b/rb. But what if I were to build a smalll block that displaced as much as an rb? Have been doing some net surfing and found this http://www.hughesengines.com/TechArticles/1ritterracingsmallblocks.php
I realize that this block is a ton of $$$, but no matter which way I go it is going to cost a truck load of $$$. That being said, what cylinder heads would work? I have a set of new brodix b1ba heads. But will they move enough air for a 440" la motor with twin turbos? Just trying to get ideas here, so if I am way off base let me know. A few other random thoughts were a 426" Hemi with a procharger or perhaps a build similar to http://www.hotrod.com/techarticles/engine/hrdp_0812_1100_hp_pump_gas_mopar_b_motor/index.html . I know these will all be high $$$ build and will take me a while to come up with the $$$...