273 Engine set up I'm thinking of going with, let me know what you think

What your engine will tolerate for octane rating isn't solely based on static CR. It's a mixture of many aspects...CR, cam timing, stall speed, gearing, weight, altitude of driving area, typical humidity, Density altitude, the intrinsic abilities of the engine itself based on flame propagation within the combustion chamber, etc. If you have a true 9.6:1 in a 273, you could run a D-dart spec cam and probably have no issues, but it's really up to what you want the engine to do.

In response to your other question about the power package, they advertise those parts to all work together, but it's not like those are the locked in components. You could run a Weiand Action Plus, with a Comp 270 solid cam, and I bet it would be a runnin' little machine, or the Edelbrock Performer with a Lunati Voodoo 262/268 grind...there are literally thousands of combinations and that's just with off the shelf parts. If you want a little lope, you could go with the thumpr line of cams...they have lots of overlap and generate that lope without killing the drivability. Keep in mind though, the thumpr cams are designed to work with lower static compression.

I guess I might want to ask a different question-what are your limits? Budget?