Usually for spark I recommend a Dyno. You can tune for street by doing it 'old school'. No KR -2 degrees, but for track and especially spray..a dyno is worth the bucks.

N/A timing depends on heads, cam, CR. My heads are 11:0.1 CR, and I run about 22-25 degrees max. A lot of the LS1 heads can take 26-28 degrees.

As far as Spray..I am not a lot of help. There was one other forum member who had some pretty bad luck spraying from the line. I am sure you can find his thread if that helps.

My final recommendation is to to tune spark on the dyno if possible.

Good luck.