Re: 429 Build?
As for the engine I am not much help, I have a lot to learn still. As for the c6, I have done plenty with those. My mods I recommend are this: if you want more rpm out of the upshift without manual selection, you can lighten up the governor weights and tune the vaccuum modulator until you get stiff shifts. This will also allow a downshift at higher speeds and shouldn't have a terrible effect on the driveability of it. A transgo is a nice kit, I have used many, they work well. Excellent instructions, and good improvement.
I never did the servo upgrade, the transgo should boost the pressure there slightly and if you want a real firm 2nd shift, take the big spring out from behind the servo, that will really shift hard then but only coming into 2nd. The servo on a c6 is for the band and the band makes 2nd gear.