Dcr

In terms of anti-knock, 87 is 87.

"High is kinda relative. It depends on the fuel, the load,the build,and how you got it."
-Start with fuel cuz that's easy. We streeters have just 3 grades to choose from, and they cover a very narrow range.
-Then there's load;
A V8 A-body can be as trim as 3100pounds or as fat as 3600. That's a 16% spread.
Then gears. You can run 2.76s to 4.30s and beyond, with first gears from 3.09 to 2.45, and clutches to all kinds of stalls.And the there's altitude.And carbs vary from around 500cfm to 750 and beyond. And fresh air versus hot underhood air. This is really complicated.
-Next is build;
things like chamber shape, quench,material, ability to shed heat,induction/exhaust,and all kinds of other parameters.
- And finally,How you got it.
If your combo has a large spread between Dcr and Scr, you might be in trouble. The fuel still has to support the Scr sooner or later. If your combo has a small spread, it might be fuel friendly.
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As to your combo; a 1.75spread, topping out at 9.75/10.0, With your listed parts in a lightweight Swinger, it should be fine. And if it turns out not to be fine, there are still several things to try, before digging into it. That's the beauty of a Zero or near-zero deck engine. Options.
Now I have to admit, there's lots of smarter guys than me on this topic. Lots and lots.
I don't know if it's possible to design a perfect Dcr to Scr spread, cuz it's kindof ethereal. Every time you change one parameter it effects others. This is where trusting your builder comes in. The Mopar builders who have been doing it for years, know what works with what.So if you just want to drop it in and drive, find one you can trust.But if you enjoy the getting there,like I did,and have the resources,aim high.

And please reread post #4.It would be hard to top moper's comments using as few words as he did.