ORIGINAL: buzzard bait
Since the entire radio and power system would be under 3 oz., I don't think less than 10 oz. would be hard to achieve.
It should be fine with 10 oz. AUW and give good scale performance.
The motor I referenced was a 24 gram 1300 kV model. I'm running the 1500kV models on 2s 1000 mAh packs -- they will turn a 8x4 high speed electric prop at 8700 to 8800, but I can't run it wide open for extended periods of time without some heat generation. Our approach has been to run a little larger motor, then turn a larger prop at a lower RPM to extend flight times. These numbers are overkill for a lightly built slow flying model.
Many of the specifications will give the max rpm obtainable for a given size prop, but sometimes these are not sustainable for the entire flight without the motor getting hot.
A lot of the combinations are just trial and error and finding what works well for you. The nice thing about the 10g microbrushless and the 24g Blue Wonders is that they both use the same 30mm mount and will interchange easily. At $10 or so, you can try one of each and still be able to have 3 meals a day.
Regards,
andrew