There are a lot of different power ratings for the 350. Depends on which heads were used and which year they were from, compression ratio, cam specs, fuel delivery system(2 or 4 barrel carb or TBI or TPI, etc), variance in different year's exhaust manifold restrictions ... not to mention the transmission ratios and the rear gear.
I'd say anywhere from 13 to 17 seconds........
I'm no 1/4 miler, myself ... so I'm vaguely taking a stabb at the times.
If you post a projected HP and torque range, I'd bet the guys with dyno simulators could figure it out for you. For instance, a '69 350 cranks out a lot more power than, say a '78 350.... or look at the '04 LS 350 in the GTO.... wow!
The point is..... I bet there are a lot of guys with 350's in their Vegas that can give you their times but those times will vary from the next guy's ..... alot.
Either one.... I bet it's a lot more fun than a stock '74 140 4-banger.