Timing advance guru input needed

Wow! Thanks for all the information guys. While I do consider myself pretty educated about engines and their functionality, I've never been one to learn about the ultra finite details to edging out the perfect tune, via carb or efi. Prior to the efi conversion, I always ran an MSD dizzy without a vacuum advance, so it wasn't even there for me to tune.
I've had intentions of adding in "vacuum advance", but have been focusing more on getting fueling right first. Now that I have that done I'm working on the timing curve. This is where I started. While the intent of my initial question wasn't about the cruising curve, I appreciate the additional feedback. Maybe I'll start getting some better MPG with the "vacuum advance" in there.