I am running HOT cam with AL fast burn heads...when you say Vortec are you referring to those heads?
If so I can provide my jetting with 750(s)..I fattened considerably with those heads.
Reading plugs with today's clean non leaded fuel is difficult...I ended up running WOT and fattening until top speed dropped/no longer increased and moved back a jet size..

Lane

I am running gm cast iron vortec heads. What jets are you running? What displacement engine?

Not sure the iron heads are comparable to the lean combustion in the fast burn setup. I ran mid 90's corvette head (initial jetting) and then bought GM parts over the counter to build/match the ZZ430..great low end torque. 350 ci x2 sea level with 10% leaded racegas..

Pri
70-78-80-78

Sec
83-86-88-87

Starting point to final setting after multiple runs...

Lane