12's from a 340 naturally aspirated.

I am running 3:91 gears on a 29" tire with a 18-spline a body 4-speed.

Thats your problem!
29" tall 3.91.
Most people running that tall, of a tire, are running 4.56 or more gear.
Try a 26" tire or 4.56 gear. That will bring your 60" down.

Can't help you with a stick, never raced with one. That first gear, you must have to slide the clutch for forever, or bog it when you leave the line.
2.40 60' is were you have plenty room for improvement.
You should be geared so that you turn on your shift light at the finish line. you need gearing. shorter tires and more gearing.
I'm not sure what you shift at, but trapping at 4900 rpm, leave a lot on the table