I took some video of this car running low 8's at Beech Bend several years ago. If you've seen the Monster Garage episode, where Jesse James turns a '74 Vette into a 4 wheel drive mud-bogger, my video was shown in the opening segments of the show.
What the top of the heap? ET and MPH, for any mod level of LT5.
If you want to qualify it by being "streetable" it would probably be one of the Lingenfelter twin turbo guys - only 4 of them around - I think 9.50s @ 145ish. Further qualifying by "streetable" and naturally aspirated, I think it's still SW's old 415 at 10.40 @ 135.