RE: slow stick prop choices versus flight performance
There's a lot of variables, how heavy your Slow Stick is, even the altitude of where you live. I live at sea level so what works for me may not work for someone who lives in a mountain area. I tried 1260 first and I did not have enough output from my battery to use that. You have plenty of power in your 2S battery so for you I would recommend the 1260. Don't even try to fly in wind more than 10mph, but the 1180 might be better if you're flying in a very light wind. Expect that your motor will start to loose power and you will need to replace it. It happens with all brushed motors. I couldn't find a replacement 300 and have been using 350 motors. The 350 requires more amps and requires that a smaller size prop be used. The 1260 with your battery would burn-up a 350 very quickly.
Here's a tool that you should try. [link=http://brantuas.com/ezcalc/dma.asp]P-Calc[/link] It a motor calculator. Input the motor, (your 300 is equivalent to Graupner Speed 280 6V), your battery, gear, prop diameter and pitch, and it will show you the estimate amps, thrust, and speed. Good tool to know about; very helpful in trying different motor, gear, prop combinations. Experiment with your Slow Stick! Find out what good for slow, easy flight and what's good for go-fast loops and climbs.