340 dog out of the hole/no low end torque??

Hey guys , I have a old problem from last summer that I haven't addressed yet, my 340 duster seems to be a slug off the get go for whats been done too it. I've yet to take it to the track (this summer I will get you all times)
I've only tested lightly on the street, and from a stand still, on the 2step, it just barley hazes the tires and comes out slow until about 4200rpm. (I have a video I can try and share)
To me it feels like symptoms of to little convertor, but I had recently installed a 3500-3800 stall TCI.

Here is my combo.
340- .40 over balanced
Air gap intake
Holley 750
150 shot nitrous(not used during tests yet)
Eddy heads rpm
Digital 6plus MSD
Lunati cam 60405
Ad dur 284/292
@50. 242/252
Lift. 533/552
Lsa/icl 110/106
Rpm range 2500-6600
727 trans
TCI 3500-3800 stall
8 3/4 rear with 4:30 gears
315/60/15 Mickey Thompson drag radial.

I've replaced everything on the car EXCEPT the transmission. Supposly from previous owner has a shift kit......

My engine was built by a respected engine builder in my city, and I didn't like my first camshaft and replaced it with the lunati.
Both have produced shitty vacuum at idle.(4-4.5")

My timing is set 21 degrees initial 34 total. I'm gonna lock it out at 34 this spring.

Does anyone have any ideas why it might be so lazy. Too much tire???
I'm gonna try and post some videos.
Thanks for the help guys. If I've left anything out let me know