13.3's to 11.8's to Forget it...

I had a 340 in my car for a couple seasons.
About 3500lbs race weight...... lots of gear, not enough stall(they missed on the set up), similar sized cam as what you had.
Went a best of 11.66@117.
Mid-1.60 60’ time.

5.13’s, 30” tires, 4800 stall.
Shift at 7500, through the lights at 6900.
It really needed 5.38’s and another 700 stall....... but that probably wouldn’t have changed the ET more than a tenth.

If you shifted lower, it slowed right down.
The converter was locked up too tight at 7500, so the fall back after the shift was too much.
(That converter worked a lot better behind the 383 I ran years later)

It just didn’t “feel” very fast, so I got bored with it....... and put the 448 back in.
It was fun when people would come look under the hood and seeing their reaction when they saw the small block in the 68 B Body running 11’s.
That wasn’t too common 25 years ago.