If memory serves correct, which it probably doesn't

There was a guy that did do a mild build on a 3.8 n/a. I can't remember what trans and rear gears he had but his regal ran 15.4 in the quarter on a mild build and 9.5 to 1 compression. If I was gonna build an n/a, I would do a 4.1 if the price was reasonable-in the n/a build, bigger is better. But then, if you are gonna build a bad ass buick 6, why not turbo it? Draw thru setups can be had for 500 or less and are plenty of fun for what money you spend on it.
If you don't have the motor assembled yet and decide NOT to go the v6 n/a route, I HIGHLY suggest putting turbo pistons in it so you can get your money back out of it. It may not have the turbo crank in it but it is plenty strong for a draw through car.