Ok Im new to the drag world but I love it and been dumping money into a 454 BBC. I finally realize my mechanic is an idiot and only knows the basic about engine building. I feel like we are putting the time and money into the wrong places so hopefully you guys can tell me what's wrong here's what I know about the engine and the results I got

2 bolt main 30 over
Srp forged 30 over pistons
Eagle h beam forged rods
Scat cast Steel crank
620 lift on cam w setup
Msd 6la distributor coil and timing control
800 Holley bp
Weiland dual plain intake
Stock oval port heads no work and don't know the casting
Also has nitrous shot on it but I'll get into that
Th400 w 23-28 stall
Exhaust cut outs

Ok 1st pass 1/4 I ran a 12.82 @ 107 373s 125shot 28" street slicks
Now today I ran 12.77 @ 103.7 456s 250shot 31.5" true drag radials.
PLEASE HELP AND TELL ME WHATS WRONG
82 C10 5200 w me n bbc