Totally agree with Dave 72! It's in the 60' But, there could be some time hiding in the incrementals, too. Your back end incremental is only .03 second slower than my record run! Your gains will be in the first 1/8 mile.
Just for grins and giggles give this a shot.
Try to slip the clutch instead of the tires until the car is moving some. If you're already doing that, play with the full engagement points. Don't worry about controlled spin on the shifts, the tire is storing momentum which it will use to push the car forward when it bites. Uncontrolled slip is another story and that is identified by the back end trying to switch with the front. Disengage the clutch just enough to unload the trans to make the shift w/o killing it. When I drove a stick car that was about half pedal travel. Maybe a bit more for 2-3 because of the forward and across gate.
Shift 1-2 @ 5000 Car now has momentum, load the engine some. Promotes cylider pressure.
Shift 2-3 @ 5500 Loads motor again.
Shift 3-4 @ 5500 and then let it eat!
See what happens to the incrementals.
Launch technique will affect 60'.
I was going to say you have too much gear but with a 340 stick you might need it to get the car moving w/o bogging. It's a little less busy with a converter.
My set up is similar to yours but with a 904 and 4000 stall behind a 360, stock heads, 486 cam, 9.8 compression, RPM air gap manifold and 650 Holley HP. Jetting was 72 P/74S. Air was 84' above sea level and I'm on 26" Mickey Thompon ET Drags. I think your tires are about the same diameter as mine.
Launch RPM was 2500 to smack the converter and shift points 1-2 @ 5200 and 2-3 @ 4635. The 1-2 was a error as I set the light at 4800. I short shifted to third to make up for it and it worked. This is the record for me.
60' 1.714
330' 5.145
660' 8.075
MPH 83.74
1000' 10.629
1/4 12.803
MPH 103.87
By contrast this run made 40 minutes before when the air was 214' came out like this
60' 1.714
330' 5.149
660' 8.091
MPH 83.13
1000' 10.649
1/4 12.826
MPH 103.06
1-2 @5310
2-3 @ 5620 (on the rev limiter for a tenth of a second)
I had the shift light brightness set too low (accidentally) and definately missed the 4800/4900 set points! This would have been the record run to be broken by the next had I been on my game!
The point is, when I load the motor by short shifting it runs harder. I can feel it in the seat and the accelerometer in the data logger shows it too. These runs were from 2005 and I've never had air this good for comparison since. Also, when I switched out the 4.10 to the 3.55 it was worth a half second. A taller tire would accomplish the same effect. High RPM isn't always the answer with these motors. I discovered this during the 01 season with a 2 channel playback tach that downloaded into my laptop. Found the driveshaft speed graph looked like an abreviated parabollic curve. Found the apex and set shift points below it. Experimented with lower points until finding the loss point between gears. In other words, overlayed driveshaft curves parallel in both lower and higher gear. Depending on weather I can shift at 4500 or 5000 with no difference in accelerometer reading or driveshaft curve. Went from a 14.214 second car to a 13.80 car overnight, literally, with no other changes than driver input. Was shifting at 6000 prior to learning this. My first national win was in my second competitive race after sitting out for 30 years to raise my kids as a result.
And people say drag racing is simple!