340 Help. Am I looking in the right spot to fix the issue

Ok answer a bunch of questions
I appreciate the thoughts.
The motor is very Lazy it accelerates like a diesel above 3000 grand.

Thermoquad has full WOT I have been building them for 15 years. 2 different carbs 800 with 98 143 1997 rods 850 100 143 1996 rods same results.
Fuel filter, Mopar metal, is before an edelbrock high flow pump 110 gpm 6 psi

Entire fuel system was new 14 years ago, all stainless new sock. Everything is tan and I read down into the plug and it is dark so it looks less likely since it has not gone dead lean.

I had a previous 340, that a cylinder cracked, set up the same and it pulled much harder. The springs are the correct ones for the cam, they where reused.

Another bit of info car gets horrible fuel economy cruising on the highway, which also relates to power dropping off, cruise at 3000 rpm right where the power drops off on the dyno graph. Previous 340 got 17 on highway cruising this struggles for 15. Almost identical builds.

I know there is 5° of advance built in but if it is put in 8° advance wouldn't it peak really early and just have nothing over 4000 rpm.

So I am pulling the distributor checking the timing plate reset timing and run it
Next I guess larger 2ndary jets 151
Next disassemble engine check degree the cam to spec of 107.