2nd try? On the cheap friendly comp?

So are we comparing $ to ET? Or just overall cost? Seems like it's just completely subjective with no clear formula to gauge the success of an entry.
Yes and no, stop the worry and have fun.
I doubt there will ever be a clear winner.
If I continue with the BB Duster, it's a loose loose except if you want or need a big block Duster in your life.

My '79 Magnum would be a better entry. It's entrance depends on my son in law. If he wants to take over the Duster and join in on this. He is all ready a mechanic, so coming home and screwing with a car is just... More work.

My Magnum (FWIW) is a $500 car
Not a bad start. Add a given (free) drivetrain and add headers intake (new) and a few used parts, carb, air cleaner, used exhaust pipes and mufflers.

I know of a parts car I could buy for $400, and sell $1000 worth of parts from it. Is that allowed to start with a car that cost -$600?

YES! And explain it like that! This would be excellent to show! And the money gained from said entry is of course rolled over into speed parts or what ever the car needs.
BRAVO MOVE!

I agree with 318's out look on the manual valve body use. If you feel you HAVE TO USE IT, well, use it but I just don't see it in a new guys car living in the street for a long time. Something's do not leave a lasting smile on your face.