12 Second N/A Slant 6?

You could be in the 13's and be fully streetable with 3.55 or 3.73 gears if you could get the rear wheel HP in the 200 to 230 range and a weight around 2600 lbs.That's about the same as a ,let's say,a stock 340 Duster.So many variables have to be delt with to get the right combo.
One of your questions was off set crank grinding.I have a 225 bored .020 over with a offset ground crank that yields 234 cubes.Maybe money not well spent for 9 more cubes.But just wanted to try something different.My engine guy wasn't used to doing any slants,Hemi's are his thing thus only a .020 overbore forgetting that a 225 block is easy to find and not worth very much. I wanted to go with a .100 over bore. for more cubes.That was 10 years ago.Now there is so much more info out there using lite weight metric pistons, rods, and rings that will yield more power.It's all about finding that right combination.(one of the reasons your '06 car runs the way it does)There is a guy that is running 12oh's in Pa N/A. He is using a fairly easy engine combo but the car's secret is he got the weight down to about 2000 lbs. With enough though any goal can be reached. Just a thought.