Thanks Chris. Your target motors are the LY6 or its replacement the L96. Use your front cover in place of theirs with the VVT and you can use your heads for more torque or use theirs for more horsepower. In the 2500s those engines got 10 city and 15 highway; kinda like what I get now with my 5.3!
Noted: LY6 and L96.
I'll definitely aim for more TQ. I have a set of mildly worked 243s from a Z06 (hollow and sodium-filled valves). I don't recall how much better they flow, but I have the flowbench results somewhere. They have Comp trunnions and dual springs as they were slated to go on an LQ9 (iron LS2 build). I'll probably swap the yellow springs back on since I'll have a stock or mild cam.
You think it was the truck and gearing that returned such crappy MPG? I mean, does .7 liters drink
that much more? It would have more TQ and be pulling less weight in my Tahoe. So, with a proper tune, it should get about the same as my 5.3, right?